The present invention relates to the compounds that modulate the activity of the endothelin family of peptides. In particular, the invention relates to the use of sulfonamides and sulfonamide pro-drugs as endothelin agonists and antagonists.
The vascular endothelium releases a variety of vasoactive substances, including the endothelium-derived vasoconstrictor peptide, endothelin (ET) (see, e.g., Vanhoutte et al. (1986) Annual Rev. Physiol. 48: 307-320; Furchgott and Zawadski (1980) Nature 288: 373-376). Endothelin, which was originally identified in the culture supernatant of porcine aortic endothelial cells (see, Yanagisawa et al. (1988) Nature 332: 411-415), is a potent twenty-one amino acid peptide vasoconstrictor. It is the most potent vasopressor known and is produced by numerous cell types, including the cells of the endothelium, trachea, kidney and brain. Endothelin is synthesized as a two hundred and three amino acid precursor preproendothelin that contains a signal sequence which is cleaved by an endogenous protease to produce a thirty-eight (human) or thirty-nine (porcine) amino acid peptide. This intermediate, referred to as big endothelin, is processed in vivo to the mature biologically active form by a putative endothelin-converting enzyme (ECE) that appears to be a metal-dependent neutral protease (see, e.g., Kashiwabara et al. (1989) FEBS Lttrs. 247: 337-340). Cleavage is required for induction of physiological responses (see, e.g., von Geldern et al. (1991) Peptide Res. 4: 32-35). In porcine aortic endothelial cells, the thirty-nine amino acid intermediate, big endothelin, is hydrolyzed at the Trp21-Val22 bond to generate endothelin-1 and a C-terminal fragment. A similar cleavage occurs in human cells from a thirty-eight amino acid intermediate. Three distinct endothelin isopeptides, endothelin-1, endothelin-2 and endothelin-3, that exhibit potent vasoconstrictor activity have been identified.
The family of three isopeptides endothelin-1, endothelin-2 and endothelin-3 are encoded by a family of three genes (see, Inoue et al. (1989) Proc. Natl. Acad. Sci. USA 86: 2863-2867; see, also Saida et al. (1989) J. Biol. Chem. 264: 14613-14616). The nucleotide sequences of the three human genes are highly conserved within the region encoding the mature 21 amino acid peptides and the C-terminal portions of the peptides are identical. Endothelin-2 is (Trp6,Leu7) endothelin-1 and endothelin-3 is (Thr2,Phe4,Thr5,Tyr6,Lys7,Tyr14) endothelin-1. These peptides are, thus, highly conserved at the C-terminal ends. Release of endothelins from cultured endothelial cells is modulated by a variety of chemical and physical stimuli and appears to be regulated at the level of transcription and/or translation. Expression of the gene encoding endothelin-1 is increased by chemical stimuli, including adrenaline, thrombin and Ca2+ ionophore. The production and release of endothelin from the endothelium is stimulated by angiotensin II, vasopressin, endotoxin, cyclosporine and other factors (see, Brooks et al. (1991) Eur. J. Pharm. 194:115-117), and is inhibited by nitric oxide. Endothelial cells appear to secrete short-lived endothelium-derived relaxing factors (EDRF), including nitric oxide or a related substance (Palmer et al. (1987) Nature 327: 524-526), when stimulated by vasoactive agents, such as acetylcholine and bradykinin. Endothelin-induced vasoconstriction is also attenuated by atrial natriuretic peptide (ANP).
The endothelin peptides exhibit numerous biological activities in vitro and in vivo. Endothelin provokes a strong and sustained vasoconstriction in vivo in rats and in isolated vascular smooth muscle preparations; it also provokes the release of eicosanoids and endothelium-derived relaxing factor (EDRF) from perfused vascular beds. Intravenous administration of endothelin-1 and in vitro addition to vascular and other smooth muscle tissues produce long-lasting pressor effects and contraction, respectively (see, e.g., Bolger et al. (1991) Can. J. Physiol. Pharmacol. 69: 406-413). In isolated vascular strips, for example, endothelin-1 is a potent (EC50=4xc3x9710xe2x88x9210 M), slow acting, but persistent, contractile agent. In vivo, a single dose elevates blood pressure in about twenty to thirty minutes. Endothelin-induced vasoconstriction is not affected by antagonists to known neurotransmitters or hormonal factors, but is abolished by calcium channel antagonists. The effect of calcium channel antagonists, however, is most likely the result of inhibition of calcium influx, since calcium influx appears to be required for the long-lasting contractile response to endothelin.
Endothelin also mediates renin release, stimulates ANP release and induces a positive inotropic action in guinea pig atria. In the lung, endothelin-1 acts as a potent bronchoconstrictor (Maggi et al. (1989) Eur. J. Pharmacol. 160: 179-182). Endothelin increases renal vascular resistance, decreases renal blood flow, and decreases glomerular filtrate rate. It is a potent mitogen for glomerular mesangial cells and invokes the phosphoinoside cascade in such cells (Simonson et al. (1990) J. Clin. Invest. 85: 790-797).
There are specific high affinity binding sites (dissociation constants in the range of 2-6xc3x9710xe2x88x9210 M) for the endothelins in the vascular system and in other tissues, including the intestine, heart, lungs, kidneys, spleen, adrenal glands and brain. Binding is not inhibited by catecholamines, vasoactive peptides, neurotoxins or calcium channel antagonists. Endothelin binds and interacts with receptor sites that are distinct from other autonomic receptors and voltage dependent calcium channels. Competitive binding studies indicate that there are multiple classes of receptors with different affinities for the endothelin isopeptides. The sarafotoxins, a group of peptide toxins from the venom of the snake Atractaspis eingadensis that cause severe coronary vasospasm in snake bite victims, have structural and functional homology to endothelin-1 and bind competitively to the same cardiac membrane receptors (Kloog et al. (1989) Trends Pharmacol. Sci. 10: 212-214).
Two distinct endothelin receptors, designated ETA and ETB, have been identified and DNA clones encoding each receptor have been isolated (Arai et al. (1990) Nature 348: 730-732; Sakurai et al. (1990) Nature 348: 732-735). Based on the amino acid sequences of the proteins encoded by the cloned DNA, it appears that each receptor contains seven membrane spanning domains and exhibits structural similarity to G-protein-coupled membrane proteins. Messenger RNA encoding both receptors has been detected in a variety of tissues, including heart, lung, kidney and brain. The distribution of receptor subtypes is tissue specific (Martin et al. (1989) Biochem. Biophys. Res. Commun. 162: 130-137). ETA receptors appear to be selective for endothelin-1 and are predominant in cardiovascular tissues. ETB receptors are predominant in noncardiovascular tissues, including the central nervous system and kidney, and interact with the three endothelin isopeptides (Sakurai et al. (1990) Nature 348: 732-734). In addition, ETA receptors occur on vascular smooth muscle, are linked to vasoconstriction and have been associated with cardiovascular, renal and central nervous system diseases; whereas ETB receptors are located on the vascular endothelium, linked to vasodilation (Takayanagi et al. (1991) FEBS Lttrs. 282: 103-106) and have been associated with bronchoconstrictive disorders.
By virtue of the distribution of receptor types and the differential affinity of each isopeptide for each receptor type, the activity of the endothelin isopeptides varies in different tissues. For example, endothelin-1 inhibits 125I-labelled endothelin-1 binding in cardiovascular tissues forty to seven hundred times more potently than endothelin-3. 125I-labelled endothelin-1 binding in non-cardiovascular tissues, such as kidney, adrenal gland, and cerebellum, is inhibited to the same extent by endothelin-1 and endothelin-3, which indicates that ETA receptors predominate in cardiovascular tissues and ETB receptors predominate in non-cardiovascular tissues.
Endothelin plasma levels are elevated in certain disease states (see, e.g., International PCT Application WO 94/27979, and U.S. Pat. No. 5,382,569, which disclosures are herein incorporated in their entirety by reference). Endothelin-1 plasma levels in healthy individuals, as measured by radioimmunoassay (RIA), are about 0.26-5 pg/ml. Blood levels of endothelin-1 and its precursor, big endothelin, are elevated in shock, myocardial infarction, vasospastic angina, kidney failure and a variety of connective tissue disorders. In patients undergoing hemodialysis or kidney transplantation or suffering from cardiogenic shock, myocardial infarction or pulmonary hypertension levels as high as 35 pg/ml have been observed (see, Stewart et al. (1991) Annals Internal Med. 114: 464-469). Because endothelin is likely to be a local, rather than a systemic, regulating factor, it is probable that the levels of endothelin at the endothelium/smooth muscle interface are much higher than circulating levels.
Elevated levels of endothelin have also been measured in patients suffering from ischemic heart disease (Yasuda et al. (1990) Amer. Heart J. 119:801-806, Ray et al. (1992) Br. Heart J. 67:383-386). Circulating and tissue endothelin immunoreactivity is increased more than twofold in patients with advanced atherosclerosis (Lerman et al. (1991) New Engl. J. Med. 325:997-1001). Increased endothelin immunoreactivity has also been associated with Buerger""s disease (Kanno et al. (1990) J. Amer. Med. Assoc. 264:2868) and Raynaud""s phenomenon (Zamora et al. (1990) Lancet 336 1144-1147). Increased circulating endothelin levels were observed in patients who underwent percutaneous transluminal coronary angioplasty (PTCA) (Tahara et al. (1991) Metab. Clin. Exp. 40:1235-1237; Sanjay et al. (1991) Circulation 84(Suppl. 4):726), and in individuals (Miyauchi et al. (1992) Jpn. J. Pharmacol. 58:279P; Stewart et al. (1991) Ann. Internal Medicine 114:464-469) with pulmonary hypertension. Thus, there is clinical human data supporting the correlation between increased endothelin levels and numerous disease states.
Endothelin Agonists and Antagonists
Because endothelin is associated with certain disease states and is implicated in numerous physiological effects, compounds that can interfere with or potentiate endothelin-associated activities, such as endothelin-receptor interaction and vasoconstrictor activity, are of interest. Compounds that exhibit endothelin antagonistic activity have been identified. For example, a fermentation product of Streptomyces misakiensis, designated BE-18257B, has been identified as an ETA receptor antagonist. BE-18257B is a cyclic pentapeptide, cyclo(D-Glu-L-Ala-allo-D-Ile-L-Leu-D-Trp), which inhibits 125I-labelled endothelin-1 binding in cardiovascular tissues in a concentration-dependent manner (IC50 1.4 xcexcM in aortic smooth muscle, 0.8 xcexcM in ventricle membranes and 0.5 xcexcM in cultured aortic smooth muscle cells), but fails to inhibit binding to receptors in tissues in which ETB receptors predominate at concentrations up to 100 xcexcM. Cyclic pentapeptides related to BE-18257B, such as cyclo(D-Asp-Pro-D-Val-Leu-D-Trp) (BQ-123), have been synthesized and shown to exhibit activity as ETA receptor antagonists (see, U.S. Pat. No. 5,114,918 to Ishikawa et al.; see, also, EP A1 0 436 189 to BANYU PHARMACEUTICAL CO., LTD (Oct. 7, 1991)). Studies that measure the inhibition by these cyclic peptides of endothelin-1 binding to endothelin-specific receptors indicate that these cyclic peptides bind preferentially to ETA receptors. Other peptide and non-peptidic ETA antagonists have been identified (see, e.g., U.S. Pat. Nos. 5,352,800, 5,334,598, 5,352,659, 5,248,807, 5,240,910, 5,198,548, 5,187,195, 5,082,838). These include other cyclic pentapeptides, acyltripeptides, hexapeptide analogs, certain anthraquinone derivatives, indanecarboxylic acids, certain N-pyrimidinylbenzenesulfonamides, certain benzenesulfonamides, and certain naphthalenesulfonamides (Nakajima et al. (1991) J. Antibiot. 44:1348-1356; Miyata et al. (1992) J. Antibiot. 45:74-8; Ishikawa et al. (1992) J. Med. Chem. 35:2139-2142; U.S. Pat. No. 5,114,918 to Ishikawa et al.; EP A1 0 569 193; EP A1 0 558 258; EP A1 0 436 189 to BANYU PHARMACEUTICAL CO., LTD (Oct. 7, 1991); Canadian Patent Application 2,067,288; Canadian Patent Application 2,071,193; U.S. Pat. Nos. 5,208,243; 5,270,313; 5,464,853 to Chan et al.; Cody et al. (1993) Med. Chem. Res. 3:154-162; Miyata et al. (1992) J. Antibiot 45:1041-1046; Miyata et al. (1992) J. Antibiot 45:1029-1040, Fujimoto et al. (1992) FEBS Lett. 305:41-44; Oshashi et al. (1002) J. Antibiot 45:1684-1685; EP A1 0 496 452; Clozel et al. (1993) Nature 365:759-761; International Patent Application WO93/08799; Nishikibe et al. (1993) Life Sci. 52:717-724; and Benigni et al. (1993) Kidney Int. 44:440-444). In general, the identified compounds have activities in in vitro assays as ETA antagonists at concentrations on the order of about 50-100 xcexcM or less. A number of such compounds have also been shown to possess activity in in vivo animal models. Very few selective ETB antagonists have been identified.
Endothelin Antagonists and Agonists as Therapeutic Agents
It has been recognized that compounds that exhibit activity at IC50 or EC50 concentrations on the order of 10xe2x88x924 or lower in standard in vitro assays that assess endothelin antagonist or agonist activity have pharmacological utility (see, em., U.S. Pat. Nos. 5,352,800, 5,334,598, 5,352,659, 5,248,807, 5,240,910, 5,198,548, 5,187,195, 5,082,838). By virtue of this activity, such compounds are considered to be useful for the treatment of hypertension such as peripheral circulatory failure, heart disease such as angina pectoris, cardio-myopathy, arteriosclerosis, myocardial infarction, pulmonary hypertension, vasospasm, vascular restenosis, Raynaud""s disease, cerebral stroke such as cerebral arterial spasm, cerebral ischemia, late phase cerebral spasm after subarachnoid hemorrhage, asthma, bronchoconstriction, renal failure, particularly post-ischemic renal failure, cyclosporine nephrotoxicity such as acute renal failure, colitis, as well as other inflammatory diseases, endotoxic shock caused by or associated with endothelin, and other diseases in which endothelin has been implicated.
In view of the numerous physiological effects of endothelin and its association with certain diseases, endothelin is believed to play a critical role in these pathophysiological conditions (see, e.g., Saito et al. (1990) Hypertension 15: 734-738; Tomita et al. (1989) N. Engl. J. Med. 321: 1127; Kurihara et al. (1989) J. Cardiovasc. Pharmacol. 13(Suppl. 5): S13-S17; Doherty (1992) J. Med. Chem. 35: 1493-1508; Morel et al. (1989) Eur. J. Pharmacol. 167: 427-428). More detailed knowledge of the function and structure of the endothelin peptide family should provide insight in the progression and treatment of such conditions.
To aid in gaining further understanding of and to develop treatments for endothelin-mediated or related disorders, there is a need to identify compounds that modulate or alter endothelin activity. Identification of compounds that modulate endothelin activity, such as those that act as specific antagonists or agonists, may not only aid in elucidating the function of endothelin, but may yield in therapeutically useful compounds. In particular, compounds that specifically interfere with the interaction of endothelin peptides with the ETA or ETB receptors should be useful in identifying essential characteristics of endothelin peptides, should aid in the design of therapeutic agents, and may be useful as disease specific therapeutic agents.
Therefore, it is an object herein to provide compounds that have the ability to modulate the biological activity of one or more of the endothelin isopeptides. It is another object to provide compounds that have use as specific endothelin antagonists. It is also an object to use compounds that specifically interact with or inhibit the interaction of endothelin peptides with ETA or ETB receptors. Such compounds should be useful as therapeutic agents for the treatment of endothelin-mediated diseases and disorders and also for the identification of endothelin receptor subtypes.
Sulfonamides and methods for modulating the interaction of an endothelin peptide with ETA and/or ETB receptors are provided. In particular, sulfonamides and methods for inhibiting the binding of an endothelin peptide to ETA or ETB receptors are provided. The methods are effected by contacting the receptors with one or more sulfonamides prior to, simultaneously with, or subsequent to contacting the receptors with an endothelin peptide. The sulfonamides are substituted or unsubstituted monocyclic or polycyclic aromatic or heteroaromatic sulfonamides, such as benzene sulfonamides, naphthalene sulfonamides and thiophene sulfonamides. Particularly preferred sulfonamides are N-isoxazolyl sulfonamides. More particularly preferred among such sulfonamides are those in which Ar2 is a heterocycle that contains one ring, multiple rings or fused rings, typically two or three rings and one or two heteroatoms in the ring or rings.
The sulfonamides have formula I: 
in which Ar1 is a substituted or unsubstituted aryl group with one or more substituents, including an alkyl group, an aryl group, a substituted aryl group, a nitro group, an amino group or a halide or is an alkyl group. In particular, Ar1 is alkyl or is a five or six membered substituted or unsubstituted aromatic or heteroaromatic ring, particularly 3- or 5-isoxazolyl and pyridazinyl, and also including thiazolyl, including 2-thiazolyl, pyrimidinyl, including 2-pyrimidinyl, or substituted benzene groups, including aryloxy substituted benzene groups or is a bicyclic or tricyclic carbon or heterocyclic ring.
Ar1 is, in certain embodiments, selected from groups such as: 
and R is selected from H, NH2, halide, pseudohalide, alkyl, alkylcarbonyl, formyl, an aromatic or heteroaromatic group, alkoxyalkyl, alkylamino, alkylthio, arylcarbonyl, aryloxy, arylamino, arylthio, haloalkyl, haloaryl, carbonyl, in which the aryl and alkyl portions, are unsubstituted or substituted with any of the preceding groups, and straight or branched chains of from about 1 up to about 10-12 carbons, preferably, 1 to about 5 or 6 carbons. R is preferably H, NH2, halide, CH3, CH3O or another aromatic group. Ar2 is any group such that the resulting sulfonamide inhibits binding by 50%, compared to binding in the absence of the sulfonamide, of an endothelin peptide to an endothelin receptor at a concentration of less than about 100 xcexcM, except that Ar2 is not phenyl or naphthyl when Ar1 is N-(5-isoxazolyl) or N-(3-isoxazolyl) unless the isoxazole is a 4-halo-isoxazole, a 4-higher alkyl (C8 to C15)-isoxazole, or the compound is a 4-biphenyl that is unsubstituted at the 2 or 6 position on the sulfonamide-linked phenyl group.
In the embodiments described in detail herein, Ar1 is an isoxazole and compounds are represented by the formulae II: 
in which R1 and R2 are either (i), (ii) or (iii) as follows:
(i) R1 and R2 are each independently selected from H, NH2, NO2, halide, pseudohalide, alkyl, alkenyl, alkynyl, aryl, arylalkyl, heteroaryl, alkoxy, alkylamino, alkylthio, alkyloxy, haloalkyl, alkylsufinyl, alkylsulfonyl, aryloxy, arylamino, arylthio, arylsufinyl, arylsulfonyl, haloalkyl, haloaryl, alkoxycarbonyl, alkylcarbonyl, aminocarbonyl, arylcarbonyl, formyl, substituted or unsubstituted amido, substituted or unsubstituted ureido, in which the alkyl, alkenyl and alkynyl portions contain from 1 up to about 14 carbon atoms and are either straight or branched chains or cyclic, and the aryl portions contain from about 4 to about 16 carbons, except that R2 is not halide or pseudohalide; or,
(ii) R1 and R2 together form xe2x80x94(CH2)n, where n is 3 to 6; or,
(iii) R1 and R2 together form 1,3-butadienyl, and with the above proviso that Ar2 is not phenyl or naphthyl when Ar1 is N-(5-isoxazolyl) or N-(3-isoxazolyl) unless the isoxazole is a 4-halo-isoxazole, a 4-higher alkyl (C8 to C15)-isoxazole, or the compound is a 4-biphenylsulfonamide that is unsubstituted at the 2 or 6 position on the sulfonamide-linked phenyl group.
In preferred embodiments herein, R1 and R2 are each selected independently from among alkyl, lower alkenyl, lower alkynyl, lower haloalkyl, halide, pseudohalide or H, except that R2 is not halide;
Ar2 is any group such that the resulting sulfonamide inhibits binding by 50%, compared to binding in the absence of the sulfonamide, of an endothelin peptide to an endothelin receptor at a concentration of less than about 100 xcexcM, with the above proviso. In particular, Ar2 is a substituted or unsubstituted group selected from among groups including, but not limited to, the following: naphthyl, phenyl, biphenyl, quinolyl, styryl, thienyl, furyl, isoquinolyl, pyrrolyl, benzofuranyl, pyridinyl, thionaphthalyl, indolyl, alkyl, and alkenyl. It is understood that the positions indicated for substituents, including the sulfonamide groups, may be varied. Thus, for example, compounds herein encompass groups that include thiophene-3-sulfonamides and thiophene-2-sulfonamides.
In certain embodiments described in detail herein, Ar2 is a 4-biphenyl or is a single ring heterocycle, particularly a 5-membered ring, or is a fused bicyclic or tricyclic heterocycle that contains one or more, particularly one, heteroatom selected from S, O and NR42, in the ring, where R42 contains up to about 30 carbon atoms, preferably 1 to 10, more preferably 1 to 6 and is selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, alkylaryl, heterocyclyl, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl, cycloalkynyl, C(O)R15 and S(O)nR15 in which n is 0-2; R15 is hydrogen, alkyl, alkenyl, alkynyl, aryl, alkylaryl, heterocyclyl, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl, cycloalkynyl; R42 and R15 are unsubstituted or are substituted with one or more substituents each selected independently from Z, which is hydrogen, halide, pseudohalide, alkyl, alkoxy, alkenyl, alkynyl, aryl, heterocyclyl, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl, cycloalkynyl, OH, CN, C(O)R16, CO2R16, SH, S(O)nR16 in which n is 0-2, NHOH, NR12R16, NO2, N3, OR16, R12NCOR16 and CONR12R16; R16 is hydrogen, alkyl, alkenyl, alkynyl, aryl, alkylaryl, heterocyclyl, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl or cycloalkynyl; R12, which is selected independently from R42 and Z, is selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, alkylaryl, heterocyclyl, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl, cycloalkynyl, C(O)R17 and S(O)nR17 in which n is 0-2; and R17 is hydrogen, alkyl, alkenyl, alkynyl, aryl, alkylaryl, heterocyclyl, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl or cycloalkynyl; each of R42, R12, R15 and R16 may be further substituted with the any of the groups set forth for Z.
In preferred embodiments herein, R42 is aryl, such as phenyl or alkyl phenyl, hydrogen or loweralkyl.
Thus, in the compounds provided herein Ar2 includes thienyl, furyl and pyrrolyl, benzofuryl, benzopyrolyl, benzothienyl, benzo[b]furyl, benzo[b]thienyl, and indolyl (benzo[b]pyrrolyl) and 4-biphenyl, and Ar1 is preferably N-(5-isoxazolyl) or N-(3-isoxazolyl). The sulfonamides are N-isoxazolyl sulfonamides and the compounds have formula III: 
in which X is S, O or NR11 in which R11 contains up to about 30 carbon atoms, preferably 1 to 10, more preferably 1 to 6 and is selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, alkylaryl, heterocyclyl, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl, cycloalkynyl, C(O)R15 and S(O)nR15 in which n is 0-2; R15 is hydrogen, alkyl, alkenyl, alkynyl, aryl, alkylaryl, heterocyclyl, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl, cycloalkynyl; R11 and R15 are unsubstituted or are substituted with one or more substituents each selected independently from Z, which is hydrogen, halide, pseudohalide, alkyl, alkoxy, alkenyl, alkynyl, aryl, heterocyclyl, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl, cycloalkynyl, OH, CN, C(O)R16, CO2R16, SH, S(O)nR16 in which n is 0-2, NHOH, NR12R16, NO2, N3, OR16, R12NCOR16 and CONR12R16; R16 is hydrogen, alkyl, alkenyl, alkynyl, aryl, alkylaryl, heterocyclyl, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl or cycloalkynyl; R12, which is selected independently from R11 and Z, is selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, alkylaryl, heterocyclyl, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl, cycloalkynyl, C(O)R17 and S(O)nR17 in which n is 0-2; and R17 is hydrogen, alkyl, alkenyl, alkynyl, aryl, alkylaryl, heterocyclyl, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl or cycloalkynyl; each of R11, R12, R15 and R16 may be further substituted with the any of the groups set forth for Z, and R11 is preferably hydrogen, aryl, such as phenyl or alkyl phenyl, loweralkyl;
or the compounds are 4-biphenylsulfonamides in which Ar1 is preferably N-(5-isoxazolyl) or N-(3-isoxazolyl).
Among the embodiments described in detail herein, Ar2 is thienyl, furyl, pyrrolyl or a group that is a derivative or analog, as described below, of a thienyl, furyl or pyrrolyl group, including benzo[b]derivatives such as a benzo[b]-thienyl, Ar1 is N-(5-isoxazolyl) or N-(3-isoxazolyl). Ar2 has the formula IV: 
in which X is O, S or NR11, where R11 is as defined above; that can be substituted at any or all positions or is an analog or derivative of the groups of formula (IV) in which the substituents form fused aromatic, aliphatic or heterocyclic rings; and R8, R9 and R10 are each independently selected as follows from (i) or (ii):
(i) R8, R9 and R10, which each contain hydrogen or up to about 50 carbon atoms, generally up to about 30, more generally 20 or fewer, are each independently selected from hydrogen, halide, pseudohalide, alkyl, alkoxy, alkenyl, alkynyl, aryl, aryloxy, heterocyclyl, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl, cycloalkynyl, OH, CN, C(O)R18, (AcO)Cxe2x95x90CHR18xe2x80x94, CO2R18, SH, (CH2)rC(O)(CH2)nR18, (CH2)r(CHxe2x95x90CH)s(CH2)nR18, (CH2)rC(O)(CHxe2x95x90CH)s(CH2)nR18, (CH2)r(CHxe2x95x90CH)sC(O)(CH2)nR18, (CH2)rNH(CHxe2x95x90CH)s(CH2)nR18, Cxe2x95x90N(OH)(CH2)rR18(CH2)r(CHxe2x95x90CH)sNH(CH2)nR18, (CH2)rC(O)NH(CH2)nR18, C(O)(CH2)rNH(CH2)nR18, (CH2)rNH(CH2)nR18, (CH2)rR18, S(O)mR18 in which m is 0-2, s, n and r are each independently 0 to 6, preferably 0-3, HNOH, NR18R19, NO2, N3, OR18, R19NCOR18 and CONR19R18, in which R19 is selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, alkylaryl, alkoxy, aryloxy, heterocyclyl, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl, cycloalkynyl, C(O)R20, S(O)nR20 in which n is 0-2; and R18 and R20 are independently selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, heteroaryl, alkylaryl, heterocyclyl, alkoxy, aryloxy, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl or cycloalkynyl; and any of the groups set forth for R8, R9 and R10 are unsubstituted or substituted with any substituents set forth for Z, which is hydrogen, halide, pseudohalide, alkyl, alkoxy, alkenyl, alkynyl, aryl, aryloxy, heterocyclyl, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl, cycloalkynyl, OH, CN, C(O)R21, CO2R21, SH, S(O)nR21 in which n is 0-2, NHOH, NR22R21, NO2, N3, OR21, R22NCOR21 and CONR22R21; R22 is selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, alkylaryl, heterocyclyl, aralkyl, alkoxy, aralkoxy, cycloalkyl, cycloalkenyl, cycloalkynyl, C(O)R23 and S(O)nR23 in which n is 0-2; and R21 and R23 are independently selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, alkylaryl, heterocyclyl, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl or cycloalkynyl, with the proviso that if R8 is NR18R19, OR18, R19NCOR18 and CONR19R18CO2R18, (CH2)rNH(CHxe2x95x90CH)s(CH2)nR18, (CH2)r(CHxe2x95x90CH)sNH(CH2)nR18, (CH2)rC(O)NH(CH2)nR18, C(O)(CH2)rNH(CH2)nR18, (CH2)rNH(CH2)nR18 or (CH2)rR18 and R18 is an aryl group containing 5 or 6 members, then the aryl group has at least two substituents, and preferably one substituent at the 2-position relative to the linkage to the thienyl, furyl or pyrrolyl;
(ii) any two of R8, R9 and R10 with the carbon to which each is attached form an aryl, aromatic ring, heteroaromatic ring, carbocyclic or heterocyclic ring, which is saturated or unsaturated, containing from about 3 to about 16 members, preferably 3 to about 10 members, more preferably 5 to 7 members that is substituted with one or more substituents, each substituent is independently selected from Z; the other of R8, R9 and R10 is selected as in (i); and the heteroatoms are NR11, O, or S, with the proviso that Ar2 is not 5-halo-3-loweralkylbenzo[b]thienyl, 5-halo-3-loweralkylbenzo[b]furyl, 5-halo-3-loweralkylbenzo[b]pyrrolyl.
In the embodiments provided herein, the alkyl, alkynyl and alkenyl portions of each listed substituent are straight or branched chains, acyclic or cyclic, and preferably have from about 1 up to about 10 carbons; in more preferred embodiments they have from 1-6 carbons. The aryl, alicyclic, aromatic rings and heterocyclic groups can have from 3 to 16, generally, 3-7, more often 5-7 members in the rings, and may be single or fused rings. The ring size and carbon chain length are selected up to an amount that the resulting molecule binds and retains activity as an endothelin antagonist or agonist, such that the resulting compound inhibits binding by 50%, compared to binding in the absence of the sulfonamide, of an endothelin peptide to an endothelin receptor at a concentration of less than about 100 xcexcM.
In preferred embodiments of interest herein, R9 and R10 are hydrogen, halide or methyl, more preferably hydrogen or halide, and R8 is selected from CO2R18, (CH2)rC(O)(CH2)nR18, (CH2)r(CHxe2x95x90CH)s(CH2)nR18, Cxe2x95x90N(OH)(CH2)rR18, (CH2)rC(O)(CHxe2x95x90CH)s(CH2)nR18, (CH2)r(CHxe2x95x90CH)sC(O)(CH2)nR18, (CH2)rNH(CHxe2x95x90CH)s(CH2)nR18, (CH2)r(CHxe2x95x90CH)sNH(CH2)nR18, (CH2)rC(O)NH(CH2)nR18, C(O)(CH2)rNH(CH2)nR18, (CH2)rNH(CH2)nR18, (CH2)rR18, with the proviso that if R8 is CO2R18, (CH2)rC(O)NH(CH2)nR18, C(O)(CH2)rNH(CH2)nR18, (CH2)rC(O)NH(CH2)nR18 or (CH2)rR18 and R18 is phenyl, the phenyl group is substituted in at least two positions, and preferably, at least one of those positions is ortho.
In the preferred compounds, R18 is aryl or heteroaryl, preferably having 5 or 6 members in the ring, more preferably phenyl or pyrimidinyl, most preferably phenyl.
In the most preferred compounds herein, R18 is phenyl, which is substituted at more than one position, and most preferably at least one substituent is at the ortho position, R9 and R10 are each hydrogen, halide or loweralkyl, preferably hydrogen, and R8 is C(O)NHR18, C(O)CH2R18, (CH2)R18, with the proviso that if R8 is C(O)NHR18, then the phenyl group must have at least two substituents, preferably one of the substituents is in the ortho position.
In other preferred embodiments, Ar2 is a benzo[b]thienyl, benzo[b]furyl, or indolyl (benzo[b]pyrrolyl), with the proviso that the benzene ring is substituted and the substituents are other than 5 halo, 3-loweralkyl. Preferred substituents on the benzene ring, include, but are not limited to, one or more selected from alkylenedioxy, particularly methylenedioxy, preferably 3,4-methylenedioxy, ethylenedioxy, aryl, particularly phenyl, dimethylamino, diethylamino, benzyl, alkoxy, particularly lower alkoxy, such as methoxy and ethoxy, halide, and alkyl, preferably loweralkyl.
In the preferred compounds herein, R2 is preferably selected from among alkyl, lower alkenyl, lower alkynyl, lower haloalkyl or H; and R1 is halide or loweralkyl, and more preferably, R1 is bromide or chloride, methyl or ethyl. In the most active compounds provided herein, as evidenced by in vitro binding assays, R1 is bromide or chloride. For use in vivo R1 is preferably chloride.
Of the compounds described herein, those that inhibit or increase an endothelin-mediated activity by about 50% at concentrations of less than about 10 xcexcM are preferred. More preferred are those that inhibit or increase an endothelin-mediated activity by about 50% at concentrations of less than about 1 xcexcM, more preferably less than about 0.1 xcexcM, even more preferably less than about 0.01 xcexcM, and most preferably less than about 0.001 xcexcM. It is noted that, as described below, the IC50 concentration determined in the in vitro assays is a non-linear function of incubation temperature. The preferred values recited herein refer to the assays that are performed at 4xc2x0 C. When the assays are performed at 24xc2x0 C., somewhat higher (see, Table 1) IC50 concentrations are observed. Accordingly, the preferred IC50 concentrations are about 10-fold higher.
Also among the most preferred compounds for use in methods provided herein, are those that are ETA selective, i.e., they interact with ETA receptors at substantially lower concentrations (at an IC50 at least about 10-fold lower, preferably 100-fold lower) than they interact with ETB receptors. In particular, compounds that interact with ETA with an IC50 of less than about 10 xcexcM, preferably less than 1 xcexcM, more preferably less than 0.1 xcexcM, but with ETB with an IC50 of greater than about 10 xcexcM or compounds that interact with ETB with an IC50 of less than about 10 xcexcM, preferably less than 1 xcexcM, more preferably less than 0.1 xcexcM, but with ETA with an IC50 of greater than about 10 xcexcM are preferred.
Preferred compounds also include compounds that are ETB receptor selective or that bind to ETB receptors with an IC50 of less than about 1 xcexcM. ETB selective compounds interact with ETB receptors at IC50 concentrations that are at least about 10-fold lower than the concentrations at which they interact with ETA receptors. In these compounds, R2 is selected from among alkyl, lower alkenyl, lower alkynyl, lower haloalkyl, halide or H; and R1 is halide or loweralkyl, and in preferred embodiments, R1 is bromide or chloride, preferably chloride; R9 and R10 are selected independently from hydrogen, loweralkyl, preferably methyl or ethyl, or halide, and R8, which is the substituent at the 5-position (see, e.g., formulae III and IV), is aryl or a heterocyclyl, particularly phenyl and isoxazolyl, which are unsubstituted or substituted with Z, which is preferably loweralkyl or halide.
Pharmaceutical compositions formulated for administration by an appropriate route and means containing effective concentrations of one or more of the compounds provided herein or pharmaceutically acceptable salts or acids thereof that deliver amounts effective for the treatment of hypertension, stroke, asthma, shock, ocular hypertension, glaucoma, renal failure, inadequate retinal perfusion and other conditions that are in some manner mediated by an endothelin peptide or that involve vasoconstriction or whose symptoms can be ameliorated by administration of an endothelin antagonist or agonist, are also provided. Particularly preferred compositions are those that deliver amounts effective for the treatment of hypertension or renal failure. The effective amounts and concentrations are effective for ameliorating any of the symptoms of any of the disorders.
Methods for inhibiting binding of an endothelin peptide to an endothelin receptor are provided. These methods are practiced by contacting the receptor with one or more of the compounds provided herein simultaneously, prior to, or subsequent to contacting the receptor with an endothelin peptide.
Methods for treatment of endothelin-mediated disorders, including but not limited to, hypertension, asthma, shock, ocular hypertension, glaucoma, inadequate retinal perfusion and other conditions that are in some manner mediated by an endothelin peptide, or for treatment of disorder that involve vasoconstriction or that are ameliorated by administration of an endothelin antagonist or agonist are provided.
In particular, methods of treating endothelin-mediated disorders by administering effective amounts of the sulfonamides, prodrugs or other suitable derivatives of the sulfonamides are provided. In particular, methods for treating endothelin-mediated disorders, including hypertension, cardiovascular diseases, cardiac diseases including myocardial infarction, pulmonary hypertension, erythropoietin-mediated hypertension, respiratory diseases and inflammatory diseases, including asthma, bronchoconstriction, ophthalmologic diseases, gastroenteric diseases, renal failure, endotoxin shock, menstrual disorders, obstetric conditions, wounds, anaphylactic shock, hemorrhagic shock, and other diseases in which endothelin mediated physiological responses are implicated, by administering effective amounts of one or more of the compounds provided herein in pharmaceutically acceptable carriers are provided. Preferred methods of treatment are methods for treatment of hypertension and renal failure.
More preferred methods of treatment are those in which the compositions contain at least one compound that inhibits the interaction of endothelin-1 with ETA receptors at an IC50 of less than about 10 xcexcM, and preferably less than about 5 xcexcM, more preferably less than about 1 xcexcM, even more preferably less than 0.1 xcexcM, and most preferably less than 0.05 xcexcM. Other preferred methods are those in which the compositions contain one or more compounds that is (are) ETA selective or one or more compounds that is (are) ETB selective. Methods in which the compounds are ETA selective are for treatment of disorders, such as hypertension; and methods in which the compounds are ETB selective are for treatment of disorders, such as asthma, that require bronchodilation.
In practicing the methods, effective amounts of compositions containing therapeutically effective concentrations of the compounds formulated for oral, intravenous, local and topical application for the treatment of hypertension, cardiovascular diseases, cardiac diseases, including myocardial infarction, respiratory diseases, including asthma, inflammatory diseases, ophthalmologic diseases, gastroenteric diseases, renal failure, immunosuppressant-mediated renal vasoconstriction, erythropoietin-mediated vasoconstriction, endotoxin shock, anaphylactic shock, hemorrhagic shock, pulmonary hypertension, and other diseases in which endothelin mediated physiological responses are implicated are administered to an individual exhibiting the symptoms of one or more of these disorders. The amounts are effective to ameliorate or eliminate one or more symptoms of the disorders.
Methods for the identification and isolation of endothelin receptor subtypes are also provided. In particular, methods for detecting, distinguishing and isolating endothelin receptors using the disclosed compounds are provided. In particular, methods are provided for detecting, distinguishing and isolating endothelin receptors using the compounds provided herein.
In addition, methods for identifying compounds that are suitable for use in treating particular diseases based on their preferential affinity for a particular endothelin receptor subtype are also provided.
Articles of manufacture containing packaging material, a compound provided herein, which is effective for ameliorating the symptoms of an endothelin-mediated disorder, antagonizing the effects of endothelin or inhibiting binding of an endothelin peptide to an ET receptor with an IC50 of less than about 10 xcexcM, within the packaging material, and a label that indicates that the compound or salt thereof is used for antagonizing the effects of endothelin, treating an endothelin-mediated disorder, or inhibiting the binding of an endothelin peptide to an ET receptor are provided.
Also provided herein are substituted biphenyl sulfonamides that have ETB activity.
Definitions
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this invention belongs. All patents and publications referred to herein are incorporated by reference.
As used herein, endothelin (ET) peptides include peptides that have substantially the amino acid sequence of endothelin-1, endothelin-2 or endothelin-3 and that act as potent endogenous vasoconstrictor peptides.
As used herein, an endothelin-mediated condition is a condition that is caused by abnormal endothelin activity or one in which compounds that inhibit endothelin activity have therapeutic use. Such diseases include, but are not limited to hypertension, cardiovascular disease, asthma, inflammatory diseases, ophthalmologic disease, menstrual disorders, obstetric conditions, gastroenteric disease, renal failure, pulmonary hypertension, endotoxin shock, anaphylactic shock, or hemorrhagic shock. Endothelin-mediated conditions also include conditions that result from therapy with agents, such as erythropoietin and immunosuppressants, that elevate endothelin levels.
As used herein an effective amount of a compound for treating a particular disease is an amount that is sufficient to ameliorate, or in some manner reduce the symptoms associated with the disease. Such amount may be administered as a single dosage or may be administered according to a regimen, whereby it is effective. The amount may cure the disease but, typically, is administered in order to ameliorate the symptoms of the disease. Typically, repeated administration is required to achieve the desired amelioration of symptoms.
As used herein, an endothelin agonist is a compound that potentiates or exhibits a biological activity associated with or possessed by an endothelin peptide.
As used herein, an endothelin antagonist is a compound, such as a drug or an antibody, that inhibits endothelin-stimulated vasoconstriction and contraction and other endothelin-mediated physiological responses. The antagonist may act by interfering with the interaction of the endothelin with an endothelin-specific receptor or by interfering with the physiological response to or bioactivity of an endothelin isopeptide, such as vasoconstriction. Thus, as used herein, an endothelin antagonist interferes with endothelin-stimulated vasoconstriction or other response or interferes with the interaction of an endothelin with an endothelin-specific receptor, such as ETA receptors, as assessed by assays known to those of skill in the art.
The effectiveness of potential agonists and antagonists can be assessed using methods known to those of skill in the art. For example, endothelin agonist activity can be identified by its ability to stimulate vasoconstriction of isolated rat thoracic aorta or portal vein ring segments (Borges et al. (1989) xe2x80x9cTissue selectivity of endothelinxe2x80x9d Eur. J. Pharmacol. 165: 223-230). Endothelin antagonist activity can be assessed by the ability to interfere with endothelin-induced vasoconstriction. Exemplary assays are set forth in the EXAMPLES. As noted above, the preferred IC50 concentration ranges are set forth with reference to assays in which the test compound is incubated with the ET receptor-bearing cells at 4xc2x0 C. Data presented for assays in which the incubation step is performed at the less preferred 24xc2x0 C. are identified. It is understood that for purposes of comparison, these concentrations are somewhat higher than the concentrations determined at 4xc2x0 C.
As used herein, the biological activity or bioactivity of endothelin includes any activity induced, potentiated or influenced by endothelin in vivo. It also includes the ability to bind to particular receptors and to induce a functional response, such as vasoconstriction. It may be assessed by In vivo assays or by in vitro assays, such as those exemplified herein. The relevant activities include, but are not limited to, vasoconstriction, vasorelaxation and bronchodilation. For example, ETB receptors appear to be expressed in vascular endothelial cells and may mediate vasodilation and other such responses; whereas ETA receptors, which are endothelin-1-specific, occur on smooth muscle and are linked to vasoconstriction. Any assay known to those of skill in the art to measure or detect such activity may be used to assess such activity (see, e.g., Spokes et al. (1989) J. Cardiovasc. Pharmacol. 13(Suppl. 5):S191-S192; Spinella et al. (1991) Proc. Natl. Acad. Sci. USA 88: 7443-7446; Cardell et al. (1991) Neurochem. Int. 18:571-574); and the Examples herein).
As used herein, the IC50 refers to an amount, concentration or dosage of a particular test compound that achieves a 50% inhibition of a maximal response, such as binding of endothelin to tissue receptors, in an assay that measures such response.
As used herein, EC50 refers to a dosage, concentration or amount of a particular test compound that elicits a dose-dependent response at 50% of maximal expression of a particular response that is induced, provoked or potentiated by the particular test compound.
As used herein a sulfonamide that is ETA selective refers to sulfonamides that exhibit an IC50 that is at least about 10-fold lower with respect to ETA receptors than ETB receptors.
As used herein, a sulfonamide that is ETB selective refers to sulfonamides that exhibit an IC50 that is at least about 10-fold lower with respect to ETB receptors than ETA receptors.
As used herein, pharmaceutically acceptable salts, esters or other derivatives of the compounds include any salts, esters or derivatives that may be readily prepared by those of skill in this art using known methods for such derivatization and that produce compounds that may be administered to animals or humans without substantial toxic effects and that either are pharmaceutically active or are prodrugs. For example, hydroxy groups can be esterified or etherified.
As used herein, treatment means any manner in which the symptoms of a conditions, disorder or disease are ameliorated or otherwise beneficially altered. Treatment also encompasses any pharmaceutical use of the compositions herein, such as use as contraceptive agents.
As used herein, amelioration of the symptoms of a particular disorder by administration of a particular pharmaceutical composition refers to any lessening, whether permanent or temporary, lasting or transient that can be attributed to or associated with administration of the composition.
As used herein, substantially pure means sufficiently homogeneous to appear free of readily detectable impurities as determined by standard methods of analysis, such as thin layer chromatography (TLC), gel electrophoresis and high performance liquid chromatography (HPLC), used by those of skill in the art to assess such purity, or sufficiently pure such that further purification would not detectably alter the physical and chemical properties, such as enzymatic and biological activities, of the substance. Methods for purification of the compounds to produce substantially chemically pure compounds are known to those of skill in the art. A substantially chemically pure compound may, however, be a mixture of stereoisomers. In such instances, further purification might increase the specific activity of the compound.
As used herein, biological activity refers to the in vivo activities of a compound or physiological responses that result upon in vivo administration of a compound, composition or other mixture. Biological activity, thus, encompasses therapeutic effects and pharmaceutical activity of such compounds, compositions and mixtures.
As used herein, a prodrug is a compound that, upon In vivo administration, is metabolized or otherwise converted to the biologically, pharmaceutically or therapeutically active form of the compound. To produce a prodrug, the pharmaceutically active compound is modified such that the active compound will be regenerated by metabolic processes. The prodrug may be designed to alter the metabolic stability or the transport characteristics of a drug, to mask side effects or toxicity, to improve the flavor of a drug or to alter other characteristics or properties of a drug. By virtue of knowledge of pharmacodynamic processes and drug metabolism in vivo, those of skill in this art, once a pharmaceutically active compound is known, can design prodrugs of the compound (see, e.g., Nogrady (1985) Medicinal Chemistry A Biochemical Approach, Oxford University Press, New York, pages 388-392). For example, succinyl-sulfathiazole is a prodrug of 4-amino-N-(2-thiazoyl)benzenesulfonamide (sulfathiazole) that exhibits altered transport characteristics.
As used herein, acid isostere means a group that is significantly ionized at physiological pH. Examples of suitable acid isosteres include sulfo, phosphono, alkylsulfonylcarbamoyl, tetrazolyl, arylsulfonylcarbamoyl or heteroarylsulfonylcarbamoyl.
As used herein, halo or halide refers to the halogen atoms; F, Cl, Br and I.
As used herein, pseudohalides are compounds that behave substantially similar to halides. Such compounds can be used in the same manner and treated in the same manner as halides (Xxe2x88x92, in which X is a halogen, such as Cl or Br). Pseudohalides include, but are not limited to cyanide, cyanate, thiocyanate, selenocyanate and azide.
As used herein, haloalkyl refers to a loweralkyl radical in which one or more of the hydrogen atoms are replaced by halogen including, but not limited to, chloromethyl, trifluoromethyl, 1-chloro-2-fluoroethyl and the like.
As used herein, alkyl means an aliphatic hydrocarbon group that is a straight or branched chain preferably having about 1 to 12 carbon atoms in the chain. Preferred alkyl groups are loweralkyl groups which are alkyls containing 1 to about 6 carbon atoms in the chain. Branched means that one or more loweralkyl groups such as methyl, ethyl or propyl are attached to a linear alkyl chain. The alkyl group may be unsubstituted or independently substituted by one or more groups, such as, but not limited to: halo, carboxy, formyl, sulfo, sulfino, carbamoyl, amino and imino. Exemplary alkyl groups include methyl, ethyl, propyl, methanoic acid, ethanoic acid, propanoic acid, ethanesulfinic acid and ethane sulfonic acid.
As used herein the term lower describes alkyl, alkenyl and alkynyl groups containing about 6 carbon atoms or fewer. It is also used to describe aryl groups or heteroaryl groups that contain 6 or fewer atoms in the ring. Loweralkyl, lower alkenyl, and lower alkynyl refer to carbon chains having less than about 6 carbons. In preferred embodiments of the compounds provided herein that include alkyl, alkenyl, or alkynyl portions include loweralkyl, lower alkenyl, and lower alkynyl portions.
As used herein, alkenyl means an aliphatic hydrocarbon group containing a carbonxe2x80x94carbon double bond and which may be straight or branched chained having from about 2 to about 10 carbon atoms in the chain. Preferred alkenyl groups have 2 to about 4 carbon atoms in the chain. Branched means that one or more loweralkyl or lower alkenyl groups are attached to a linear alkenyl chain. The alkenyl group may be unsubstituted or independently substituted by one or more groups, such as halo, carboxy, formyl, sulfo, sulfino, carbamoyl, amino and imino. Exemplary alkenyl groups include ethenyl, propenyl, carboxyethenyl, carboxypropenyl, sulfinoethenyl and sulfonoethenyl.
As used herein, alkynyl means an aliphatic hydrocarbon group containing a carbonxe2x80x94carbon triple bond and which may be straight or branched having about 2 to 10 carbon atoms in the chain. Branched means that one or more loweralkyl, alkenyl or alkynyl groups are attached to a linear alkynyl chain. An exemplary alkynyl group is ethynyl.
As used herein, aryl means an aromatic monocyclic or multicyclic hydrocarbon ring system containing from 3 to 15 or 16 carbon atoms, preferably from 5 to 10. Aryl groups include, but are not limited to groups, such as phenyl, substituted phenyl, naphthyl, substituted naphthyl, in which the substituent is loweralkyl, halogen, or lower alkoxy. Preferred aryl groups are lower aryl groups that contain less than 7 carbons in the ring structure.
As used herein, the nomenclature alkyl, alkoxy, carbonyl, etc. are used as is generally understood by those of skill in this art. For example, as used herein alkyl refers to saturated carbon chains that contain one or more carbons; the chains may be straight or branched or include cyclic portions or be cyclic. As used herein, alicyclic refers to aryl groups that are cyclic.
As used herein, cycloalkyl refers to saturated cyclic carbon chains; cycloalkyenyl and cycloalkynyl refer to cyclic carbon chains that include at least one unsaturated double or triple bond, respectively. The cyclic portions of the carbon chains may include one ring or two or more fused rings.
As used herein, cycloalkenyl means a non-aromatic monocyclic or multicyclic ring system containing a carbonxe2x80x94carbon double bond and having about 3 to about 10 carbon atoms. Exemplary monocyclic cycloalkenyl rings include cyclopentenyl or cyclohexenyl; preferred is cyclohexenyl. An exemplary multicyclic cycloalkenyl ring is norbornylenyl. The cycloalkenyl group may be independently substituted by one or more halo or alkyl.
As used herein, xe2x80x9chaloalkylxe2x80x9d refers to a loweralkyl radical in which one or more of the hydrogen atoms are replaced by halogen including, but not limited to, chloromethyl, trifluoromethyl, 1-chloro-2-fluoroethyl and the like.
As used herein, xe2x80x9chaloalkoxyxe2x80x9d refers to ROxe2x80x94 in which R is a haloalkyl group.
As used herein, xe2x80x9ccarboxamidexe2x80x9d refers to groups of formula RpCONH2 in which R is selected from alkyl or aryl, preferably loweralkyl or lower aryl and p is 0 or 1.
As used herein, xe2x80x9calkylaminocarbonylxe2x80x9d refers to xe2x80x94C(O)NHR in which R is hydrogen, alkyl, preferably loweralkyl or aryl, preferably lower aryl.
As used herein xe2x80x9cdialkylaminocarbonylxe2x80x9d as used herein refers to xe2x80x94C(O)NRxe2x80x2R in which Rxe2x80x2 and R are independently selected from alkyl or aryl, preferably loweralkyl or loweraryl; xe2x80x9ccarboxamidexe2x80x9d refers to groups of formula NRxe2x80x2COR.
As used herein, xe2x80x9calkoxycarbonylxe2x80x9d as used herein refers to xe2x80x94C(O)OR in which R is alkyl, preferably loweralkyl or aryl, preferably lower aryl.
As used herein, xe2x80x9calkoxyxe2x80x9d and xe2x80x9cthioalkoxyxe2x80x9d refer to ROxe2x80x94 and RSxe2x80x94, in which R is alkyl, preferably loweralkyl or aryl, preferably lower aryl.
As used herein, xe2x80x9chaloalkoxyxe2x80x9d refers to ROxe2x80x94 in which R is a haloalkyl group.
As used herein, xe2x80x9caminocarbonylxe2x80x9d refers to xe2x80x94C(O)NH2.
As used herein, xe2x80x9calkylaminocarbonylxe2x80x9d refers to xe2x80x94C(O)NHR in which R is alkyl, preferably loweralkyl or aryl, preferably lower aryl.
As used herein, xe2x80x9calkoxycarbonylxe2x80x9d refers to xe2x80x94C(O)OR in which R is alkyl, preferably loweralkyl.
As used herein, cycloalkyl refers to saturated cyclic carbon chains; cycloalkenyl and cycloalkynyl refer to cyclic carbon chains that include at least one unsaturated double or triple bond. The cyclic portions of the carbon chains may include one ring or two or more fused rings.
As used herein, alkylenedioxy means an xe2x80x94O-alkyl-Oxe2x80x94 group in which the alkyl group is as previously described. A replacement analog of alkylenedioxy means an alkylenedioxy in which one or both of the oxygen atoms is replaced by a similar behaving atom or group of atoms such as, S, N, NH, Se. An exemplary replacement alkylenedioxy group is ethylenebis(sulfandiyl). Alkylenethioxyoxy is xe2x80x94S-alkyl-Oxe2x80x94, xe2x80x94O-alkyl-Sxe2x80x94 and alkylenedithioxy is xe2x80x94S-alkyl-Sxe2x80x94.
As used herein, heteroaryl means an aromatic monocyclic or fused ring system in which one or more of the carbon atoms in the ring system is(are) replaced by an element(s) other than carbon, for example nitrogen, oxygen or sulfur. Preferred cyclic groups contain one or two fused rings and include from about 3 to about 7 members in each ring. Similar to xe2x80x9caryl groupsxe2x80x9d, the heteroaryl groups may be unsubstituted or substituted by one or more substituents. Exemplary heteroaryl groups include pyrazinyl, pyrazolyl, tetrazolyl, furanyl, (2- or 3-)thienyl, (2-,3- or 4-)pyridyl, imidazoyl, pyrimidinyl, isoxazolyl, thiazolyl, isothiazolyl, quinolinyl, indolyl, isoquinolinyl, oxazolyl and 1,2,4-oxadiazolyl. Preferred heteroaryl groups include 5 to 6-membered nitrogen-containing rings, such as pyrmidinyl.
As used herein, alkoxycarbonyl means an alkyl-Oxe2x80x94COxe2x80x94 group. Exemplary alkoxycarbonyl groups include methoxy- and ethoxycarbonyl.
As used herein, carbamoyl means xe2x80x94CONH2. As with all groups described herein, these groups may be unsubstituted or substituted. Substituted carbamoyl includes groups such as xe2x80x94CONY2Y3 in which Y2 and Y3 are independently hydrogen, alkyl, cyano(loweralkyl), aryalkyl, heteroaralkyl, carboxy(loweralkyl), carboxy(aryl substituted loweralkyl), carboxy(carboxy substituted loweralkyl), carboxy(hydroxy substituted loweralkyl), carboxy(heteroaryl substituted loweralkyl), carbamoyl(loweralkyl), alkoxycarbonyl(loweralkyl) or alkoxycarbonyl(aryl substituted loweralkyl), provided that only one of Y2 and Y3 may be hydrogen and when one of Y2 and Y3 is carboxy(loweralkyl), carboxy(aryl substituted loweralkyl), carbamoyl(loweralkyl), alkoxycarbonyl(loweralkyl) or alkoxycarbonyl(aryl substituted loweralkyl) then the other of Y2 and Y3 is hydrogen or alkyl. Preferred for Y2 and Y3 are independently hydrogen, alkyl, cyano(loweralkyl), aryalkyl, heteroaralkyl, carboxy(loweralkyl), carboxy(aryl substituted loweralkyl) and carbamoyl(loweralkyl).
As used herein, any corresponding N-(4-halo-3-methyl-5-isoxazolyl), N-(4-halo-5-methyl-3-isoxazolyl), N-(3,4-dimethyl-5-isoxazolyl), N-(4-halo-5-methyl-3-isoxazolyl), N-(4-halo-3-methyl-5-isoxazolyl), N-(4,5-dimethyl-3-isoxazolyl) derivative thereof refers to compounds in which Ar2 is the same as the compound specifically set forth, but Ar1 is N-(4-halo-3-methyl-5-isoxazolyl), N-(4-halo-5-methyl-3-isoxazolyl), N-(3,4-dimethyl-5-isoxazolyl), N-(4-halo-5-methyl-3-isoxazolyl), N-(4-halo-3-methyl-5-isoxazolyl), or N-(4,5-dimethyl-3-isoxazolyl) in which halo is any halide, preferably Cl or Br.
As used herein, the abbreviations for any protective groups, amino acids and other compounds, are, unless indicated otherwise, in accord with their common usage, recognized abbreviations, or the IUPAC-IUB Commission on Biochemical Nomenclature (see, (1972) Biochem. 11:942-944).
A. Compounds for Use in Treating Endothelin-Mediated Diseases
Compounds and methods for treating endothelin-mediated diseases using the compounds of formulae I and II are provided. In particular, in the compounds provided herein, Ar2 is thienyl, furyl, pyrrolyl or a group, such as benzofuryl, thionaphthyl or indolyl, that is a derivative or analog, as described below, of a thienyl, furyl or pyrrolyl group or a 4-biphenyl group, Ar1 is preferably N-(5-isoxazolyl) or N-(3-isoxazolyl).
1. Ar2 is a Thiophene, Pyrrole, Furan, Benzo[b]Thiophene, Indolyl (Benzo[b]Pyrrole), or Benzo[b]Furan
Among the compounds provided herein are those represented by the formula V: 
in which
R1 and R2 are either (i), (ii) or (iii) as follows:
(i) R1 and R2 are each independently selected from H, NH2, NO2, halide, pseudohalide, alkyl, alkenyl, alkynyl, aryl, arylalkyl, heterolaryl, alkoxy, alkylamino, alkylthio, haloalkoxy, haloalkyl, alkylsufinyl, alkylsulfonyl, aryloxy, arylamino, arylthio, arylsufinyl, arylsulfonyl, aminocarbonyl, arylaminocarbonyl, haloalkyl, haloaryl, alkoxycarbonyl, alkylcarbonyl, arylcarbonyl, formyl, substituted or unsubstituted amido, substituted or unsubstituted ureido, in which the alkyl, alkenyl and alkynyl portions are either straight or branched chains that contain from 1 up to about 10 carbon atoms, and the aryl portions contain from about 4 to about 14 carbons, except the R2 is not halide, pseudohalide or higher alkyl; or,
(ii) R1 and R2 together form xe2x80x94(CH2)n, where n is 3 to 6; or,
(iii) R1 and R2 together form 1,3-butadienyl; and
X is S, O or NR11 in which R11 contains up to about 30 carbon atoms, preferably 1 to 10, more preferably 1 to 6 and is selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, alkylaryl, heterocycyle, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl, cycloalkynyl, C(O)R15 and S(O)nR15 in which n is 0-2; R15 is hydrogen, alkyl, alkenyl, alkynyl, aryl, alkylaryl, heterocyclyl, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl, cycloalkynyl; R11 and R15 are unsubstituted or are substituted with one or more substituents each selected independently from Z, which is hydrogen, halide, pseudohalide, alkyl, alkoxy, alkenyl, alkynyl, aryl, heterocyclyl, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl, cycloalkynyl, OH, CN, C(O)R16, CO2R16, SH, S(O)nR16 in which n is 0-2, NHOH, NR12R16, NO2, N3, OR16, R12NCOR16 and CONR12R16; R16 is hydrogen, alkyl, alkenyl, alkynyl, aryl, alkylaryl, heterocyclyl, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl or cycloalkynyl; R12, which is selected independently from R11 and Z, is selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, alkylaryl, heterocyclyl, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl, cycloalkynyl, C(O)R17 and S(O)nR17 in which n is 0-2; and R17 is hydrogen, alkyl, alkenyl, alkynyl, aryl, alkylaryl, heterocyclyl, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl or cycloalkynyl; each of R11, R12, R15 and R16 may be further substituted with the any of the groups set forth for Z, and R11 is preferably hydrogen, aryl, such as phenyl or alkyl phenyl, loweralkyl; and
R8, R9 and R10, which each contain hydrogen or up to about 50 carbon atoms, generally up to about 30, more generally 20 or fewer, are each independently selected as described above, and more preferably from (i) or (ii) as follows:
(i) R9 and R10 are selected from hydrogen, halide, pseudohalide, alkyl, alkoxy, alkenyl, alkynyl, aryl, aryloxy, heterocyclyl, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl, cycloalkynyl, OH, CN, C(O)R18, (AcO)Cxe2x95x90CHR18, CO2R18, SH, (CH2)rC(O)(CH2)nR18, (CH2)r(CHxe2x95x90CH)s(CH2)nR18, (CH2)rC(O)(CHxe2x95x90CH)s(CH2)nR18, (CH2)r(CHxe2x95x90CH)sC(O)(CH2)nR18, (CH2)rNH(CHxe2x95x90CH)s(CH2)nR18, Cxe2x95x90N(OH)(CH2)rR18, (CH2)r(CHxe2x95x90CH)sNH(CH2)nR18, (CH2)rC(O)NH(CH2)nR18, C(O)(CH2)rNH(CH2)nR18, (CH2)rNH(CH2)nR18, (CH2)rR18, S(O)mR18 in which m is 0-2, s, n and r are each independently 0 to 6, preferably 0-3, HNOH, NR18R19, NO2, N3, OR18, R19NCOR18 and CONR19R18, in which R19 is selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, alkylaryl, alkoxy, aryloxy, heterocyclyl, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl, cycloalkynyl, C(O)R20, S(O)nR20 in which n is 0-2; and R18 and R20 are independently selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, heteroaryl, alkylaryl, heterocyclyl, alkoxy, aryloxy, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl or cycloalkynyl;
R8 is selected from C(O)R18, (AcO)Cxe2x95x90CHR18, CO2R18, (CH2)rC(O)(CH2)nR18, (CH2)r(CHxe2x95x90CH)s(CH2)nR18, (CH2)rC(O)(CHxe2x95x90CH)s(CH2)nR18, (CH2)r(CHxe2x95x90CH)sC(O)(CH2)nR18, (CH2)rNH(CHxe2x95x90CH)s(CH2)nR18, Cxe2x95x90N(OH)(CH2)rR18, (CH2)r(CHxe2x95x90CH)sNH(CH2)nR18, (CH2)rC(O)NH(CH2)nR18, C(O)(CH2)rNH(CH2)nR18, (CH2)rNH(CH2)nR18, (CH2)rR18, in which m is 0-2, s, n and r are each independently 0 to 6, preferably 0-3, in which R18 is aryl, preferably phenyl, with the proviso that, if R8 is (CH2)rC(O)NH(CH2)nR18, C(O)(CH2)rNH(CH2)nR18, (CH2)rNH(CH2)nR18, (CH2)rR18, particularly if r is 0 and/or n is 0, and R18 is aryl, particularly phenyl, then R18 must have two or more substituents, with preferably at least one ortho substituent;
where any of the groups set forth for R8, R9 and R10 are unsubstituted or substituted with any substituents set forth for Z, which is hydrogen, halide, pseudohalide, alkyl, alkoxy, alkenyl, alkynyl, aryl, aryloxy, heterocyclyl, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl, cycloalkynyl, OH, CN, C(O)R21, CO2R21, SH, S(O)nR21 in which n is 0-2, NHOH, NR22R21, NO2, N3, OR21, R22NCOR21 and CONR22R21; R22 is selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, alkylaryl, heterocyclyl, aralkyl, alkoxy, aralkoxy, cycloalkyl, cycloalkenyl, cycloalkynyl, C(O)R23 and S(O)nR23 in which n is 0-2; and R21 and R23 are independently selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, alkylaryl, heterocyclyl, aralkyl, aralkoxy, cycloalkyl, cycloalkenyl or cycloalkynyl; or
(ii) any two of R8, R9 and R10 form an aryl, aromatic ring, heteroaromatic ring, carbocyclic or heterocyclic ring, which is saturated or unsaturated, containing from about 3 to about 16 members, preferably 3 to about 10 members, more preferably 5 to 7 members that is substituted with one or more substituents, each substituent being independently selected from Z; the other of R8, R9 and R10 is selected as from the groups set forth for R9 and R10 in (i); and the heteroatoms are NR11, O, or S, with the proviso that Ar2 is not 5-halo-3-loweralkylbenzo[b]thienyl, 5-halo-3-loweralkylbenzo[b]furyl, 5-halo-3-loweralkylbenzo[b]pyrrolyl.
In these embodiments, Ar2 is, thus, represented by the formulae (IVA and IVB): 
that can be substituted at any or all positions or is an analog of compounds of formula (IV) in which the substituents form fused aromatic, aliphatic or heterocyclic rings; and in which X is NR11, O, or S, and R11, which is hydrogen or contains up to about 30 carbon atoms, preferably 1 to 10, more preferably 1 to 6, and is selected as defined above. R8, R9, R10 are selected as described above.
In the embodiments provided herein, when R8, R9 and R10 are selected as in (i), above, R8 is preferably selected from among (CH2)rC(O)(CH2)nR18, (CH2)rNH(CH2)nR18, (CH2)rNH(CH2)nR18, (CH2)r(CHxe2x95x90CH)s(CH2)nR18, (CH2)rC(O)(CHxe2x95x90CH)s(CH2)nR18, (CH2)r(CHxe2x95x90CH)sC(O)(CH2)nR18, (CH2)r(CHxe2x95x90CH)sNH(CH2)nR18, Cxe2x95x90N(OH)(CH2)rR18, (CH2)rC(O)NH(CH2)nR18, C(O)(CH2)rNH(CH2)nR18, (CH2)rNH(CHxe2x95x90CH)s(CH2)nR18, (CH2)rC(O)NH(CH2)nR18, (CH2)rNH(CH2)nR18, (CH2)rR18, with the proviso that if R8 is (CH2)rC(O)NH(CH2)nR18, (CH2)rC(O)NH(CH2)nR18, or (CH2)rR18, and R18 is phenyl, the phenyl group is substituted at least two positions, and preferably, at least one of those positions is ortho.
In preferred of these compounds, R18 is aryl or heteroaryl, preferably having 5 or 6 members in the ring, more preferably phenyl or pyrimidinyl, most preferably phenyl. R9 and R10 are preferably hydrogen, halide, loweralkyl, or halo loweralkyl.
The more preferred compounds provided herein are compounds in which the alkyl, alkynyl and alkenyl portions are straight or branched chains, acyclic or cyclic, and have from about 1 up to about 10 carbons; in certain of the more preferred embodiments they have from 1-6 carbons, and they can have fewer than 6 carbons. The aryl, homocyclic and heterocyclic groups can have from 3 to 16, generally, 3-7, more often 5-7 members in the rings, and may be single or fused rings. The ring size and carbon chain length are selected such that the resulting molecule exhibits activity as an endothelin antagonist or agonist as evidenced by in vitro or in vivo tests, particularly the tests exemplified herein.
In any of the above preferred embodiments: R1 and R2 are preferably selected independently from alkyl, lower alkenyl, lower alkynyl, lower haloalkyl, halide, pseudohalide and H, except that R2 is not halide or pseudohalide, and in preferred embodiments is also not higher alkyl.
In preferred embodiments: X is S, O, NR11 in which R11 is aryl, hydrogen, or loweralkyl, preferably, a substituted or unsubstituted aryl, particularly phenyl, preferably unsubstituted or substituted with loweralkyl or halogen hydrogen or loweralkyl; R1 is hydrogen, halide, pseudohalide, loweralkyl or lower haloalkyl, most preferably halide; R2 is hydrogen, loweralkyl or lower haloalkyl.
The aryl groups are unsubstituted or is substituted with groups such as alkyl, alkoxy, alkoxyalkyl, halogen, alkylenedioxy, particularly methylene dioxy, amino, nitro and other such groups. The alkyl substituents are preferably loweralkyl, more preferably containing 1-3 carbons.
In more preferred embodiments, two of R9 and R10 are hydrogen, halide or loweralkyl and R8 is C(O)NHR18 or C(O)CH2R18 in which R18 is a phenyl group that is substituted at at least two positions, most preferably at least one substituent at the ortho position and also 3,4 or 4,5 alkylenedioxy substituents. In more preferred of these embodiments X is S.
In all embodiments, R1 is preferably halide, H, CH3 or C2H5, and R2 is H, CH3, C2H5, C2F5 or CF3. In yet more preferred embodiments, R1 preferably Br, Cl or CH3; R2 is H, CH3, C2H5, or CF3.
In other embodiments two of R8, R9 and R10 form a ring so that Ar2 is benzo[b]thienyl, benzo[b]furyl, or indolyl, with the proviso that there is one or more substituents and they are other than 5-halo and 3-loweralkyl, and the other of R8, R9 and R10 is selected from aryl, (CH2)rR18, C(O)R18, CO2R18, NR18R19, SH, S(O)nR18 in which n is 0-2, HNOH, NO2, N3, OR18, R19NCOR18 and CONR19R18. Ar2 may be further substituted with any of the groups set forth for R8, R9 and R10, and are preferably selected from among alkyl, alkoxy, alkoxyalkyl, aryl, alkylaryl, aminoalkyl, arylamino, aryl-substituted amino, and NR11.
In embodiments in which ETB antagonists are desired, it is preferred that R8 and R10 are H or loweralkyl and R9 includes heterocyclic or aromatic ring of preferably from 3 to 14, more preferably, 5 to 7, members in the ring. In particular, if X is S, R8 and R10 are H or loweralkyl, and R9, includes an aryl group, particularly a substituted phenyl, such as a 2-loweralkyl substituent. The aryl portion is substituted with groups such as alkyl, alkoxy, alkoxyalkyl, halogen, alkylenedioxy, particularly methylenedioxy, amino, nitro and other such groups. The alkyl substituents are preferably loweralkyl, more preferably containing 1-3 carbons.
If X is NR11, then R11 is aryl, particularly unsubstituted phenyl or substituted phenyl, such as isopropylphenyl.
Other preferred compounds, which are ETB active, are those in which Ar2 has formula IVB in which R9 is aryl or Z-substituted aryl, particularly phenyl, and Z is loweralkyl or loweralkoxy.
In all embodiments of all of the compounds herein R1 is preferably halide or loweralkyl, most preferably Br, and the compounds are, with reference to formulae IV, 2- or 3-sulfonamides, particularly thiophene sulfonamides. In certain embodiments provided herein, Ar2 is a benzo[b]thienyl, benzo[b]furyl or indolyl (benzo[b]pyrrolyl) group and the compounds provided herein are preferably benzo[b]thienyl-, benzo[b]furyl- or indolylsulfonamides Benzo[b]thiophene, benzo[b]furyl and indolyl 2- or 3-sulfonamides are among the compounds preferred herein. The benzo[b]thiophene, benzo[b]furyl and indolyl 2- or 3-sulfonamides provided herein are selected with the proviso that the benzene group has at least one substituent and that substituent is other than 5-halo and 3-loweralkyl.
Compounds of particular interest include those of formula III in which Ar2 is a phenyl, benzothienyl, benzofuryl or indolyl [benzopyrrolyl] group or in which Ar2 is a substituted phenylaminocarbonylthienyl, substituted phenylaminocarbonylfuryl, substituted aminocarbonylpyrrolyl group in which there are at least two substituents or Ar2 is phenylacetylthiophene, phenylacetylfuran, or phenylacetylpyrrole, is an acetoxystyrylthiophene, acetoxystyrylfuran or acetoxystyrylpyrrole.
The most preferred compounds provided herein have an IC50 for ETA receptors in the assays exemplified herein less than 0.1 xcexcM, more preferably less than 0.01 xcexcM, and more preferably less than 0.001 (see, e.g., Table 1 for representative experimental results), when measured at 4xc2x0 C., as described in the Examples. When measured at 24xc2x0 C., the IC50 concentrations are somewhat higher (2- to 10-fold; see, Table 1 for some comparative values).
Among the preferred compounds of interest herein are those in which Ar2 has formula VI: 
in which M is (CH2)mC(O)(CH2)r, (CH2)mC(O)NH(CH2)r, (CH2)m(CHxe2x95x90CH)(CH2)r, (CH2)mC(O)(CH2)sNH(CH2)r, (CH2)m(CHxe2x95x90CH)(CH2)r, Cxe2x95x90N(OH)(CH2)r, (CH2)mC(O)(CHxe2x95x90CH)sNH(CH2)r, CH(OH)(CH2)r, CH(CH3)C(O)(CH2)r, CH(CH3)C(O)(CH2)m(CHxe2x95x90CH)(CH2)r, (CH2)r, (CH2)rO, C(O)O, in which m, s and r are each independently 0 to 6, preferably 0 to 3, more preferably M is (CH2)mC(O)(CH2)r, (CH2)mC(O)NH(CH2)r, (CH2)m(CHxe2x95x90CH)(CH2)r, (CH2)mC(O)(CH2)sNH(CH2)r, (CH2)m(CHxe2x95x90CH)(CH2)r, Cxe2x95x90N(OH)(CH2)r, CH(OH)(CH2)r, (CH2)r, (CH2)rO, C(O)O;
R31, R32, R33, R34 and R35 are each independently selected from (i) or (ii) as follows:
(i) R31, R32, R33, R34 and R35 are each independently selected from among H, OH, NHR38, CONR38R39, NO2, cyano, halide, pseudohalide, alkyl, alkenyl, alkynyl, aryl, arylalkyl, heteroaryl, alkoxy, alkylamino, alkylthio, haloalkyl, alkylsulfinyl, alkylsulfonyl, alkoxycarbonyl, alkylcarbonyl, alkenylthio, alkenylamino, alkenyloxy, alkenyl sulfinyl, alkenylsulfonyl, alkoxycarbonyl, arylaminocarbonyl, alkylaminocarbonyl, aminocarbonyl, (alkylaminocarbonyl)alkyl, carboxyl, carboxyalkyl, carboxyalkenyl, alkylsulfonylaminoalkyl, cyanoalkyl, acetyl, acetoxyalkyl, hydroxyalkyl, alkyloxyalkoxy, hydroxyalkyl, (acetoxy)alkoxy, (hydroxy)alkoxy and formyl; or
(ii) at least two of R31, R32, R33, R34 and R35, which substitute adjacent carbons on the ring, together form alkylenedioxy, alkylenethioxyoxy or alkylenedithioxy (i.e. xe2x80x94Oxe2x80x94(CH2)nxe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94(CH2)nxe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94(CH2)nxe2x80x94Sxe2x80x94, where n is 1 to 4, preferably 1 or 2,) which is unsubstituted or substituted by replacing one or more hydrogens with halide, loweralkyl, loweralkoxy or halo loweralkyl, and the others of R31, R32, R33, R34 and R35 are selected as in (i); and
R38 and R39 are each independently selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, haloalkyl alkylaryl, heterocyclyl, arylalkyl, arylalkoxy, alkoxy, aryloxy, cycloalkyl, cycloalkenyl and cycloalkynyl, and is preferably hydrogen, loweralkyl, loweralkoxy and lowerhaloalkyl, with the proviso that when M is (CH2)mC(O)NH(CH2)r, then at least two of R31, R32, R33, R34 and R35 are not hydrogen.
M is most preferably 
In general, however, in all of these compounds in which Ar2 has formula V or VI or in which R8 includes an aryl group, regardless of the selection of M, it is preferred that the aryl substituent have more than one substituent or at least one substituent in the ortho position. Aryl is preferably phenyl that is preferably substituted at the ortho position and, more preferably at at least one additional position, particularly 4 and 6, or adjacent positions, such as 3,4 or 4,5 when the substituents are linked to form an alkylenedioxy (or analog thereof) in which one or both oxygens is(are) replaced with S.
In all compounds, at least one of R31 and R35 is other than hydrogen.
In more preferred compounds, M is C(O)CH2, C(O)NH, xe2x80x94CHxe2x95x90CHxe2x80x94, CH2CH2C(O)(CHxe2x95x90CH), CHxe2x95x90CHC(O)CH2, and most preferably has formula VII: 
in which W is CH2 or NH.
M is even more preferably selected from among: 
in which R40 is preferably hydrogen, alkyl, alkoxy, alkoxyalkyl, haloalkyl, and more preferably loweralkyl, loweralkoxy, or halo loweralkyl, and is more preferably hydrogen or loweralkyl, particularly methyl or ethyl, and is most preferably hydrogen.
M is most preferably: 
In preferred compounds R31, R32, R33, R34 and R35 are selected from (i) or (ii):
(i) R31, R32, R33, R34 and R35 are each independently selected from loweralkyl, haloloweralkyl, phenyl, alkoxy, loweralkylsulfonylaminoloweralkyl, cyanoloweralkyl, acetyl, loweralkoxycarbonyl, cyano, OH, acetoxyloweralkyl, hydroxy loweralkyl, acetoxy loweralkoxy or loweralkoxycarbonyl; or
(ii) R32 and R33 or R33 and R34 form alkylene dioxy, preferably methylenedioxy, and the others of R31, R32, R33, R34 and R35 are selected as in (i).
In preferred embodiments, R31, R33, R35 are other then hydrogen and are preferably loweralkyl or lower alkoxy, or R31 or R35 is other than hydrogen, preferably loweralkyl or lower alkoxy, and R32 and R33 or R33 and R34 form methylenedioxy.
In all embodiments, preferred substituents also can be determined by reference to Table 1, which sets forth exemplary compounds.
Preferred compounds are those of Table 1 that have the highest activities, and preferred substituents are those on the compounds with the highest activities.
It is understood that 4-bromo or 4-chloro groups can be replaced by other 4-halo substituents or other suitable substituents for R1, such as alkyl.
2. Ar2 is a Substituted 4-Biphenyl Group
Compounds of formulae I in which Ar1 is N-(5-isoxazolyl) or N-(3-isoxazolyl) in which Ar2 is selected from biphenyl derivatives. These compounds can be represented by the following formulae (VIII): 
in which R26 and R13 are each independently selected from H, OH, OHNH, NH2, NO2, halide, pseudohalide, alkyl, alkenyl, alkynyl, aryl, arylalkyl, heterolaryl, alkoxy, alkylamino, dialkylamino, alkylthio, haloalkoxy, haloalkyl, alkylsufinyl, alkylsulfonyl, aryloxy, arylamino, arylthio, arylsufinyl, arylsulfonyl, haloalkyl, haloaryl, alkoxycarbonyl, carbonyl, alkylcarbonyl, aminocarbonyl, arylcarbonyl, formyl, substituted or unsubstituted amido, substituted or unsubstituted ureido, in which the alkyl, alkenyl and alkynyl portions contain from 1 up to about 14 carbon atoms, preferably from 1 to 6 atoms, and are either straight or branched chains or cyclic, and the aryl portions contain from about 4 to about 16 carbons, preferably 4 to 10 carbons. R13 and R26 are preferably each selected from H, loweralkyl, haloalkyl and halide. Again, it is understood that Ar2 may be substituted with more than one substituent, each of which is selected independently from the selections set forth for R26 and R13, and R2 and R1 are as defined above.
In the embodiments herein, the biphenylsulfonamides are substituted 4-biphenylsulfonamides, R13 is preferably at the para position and R26, if it is not hydrogen, is at any position except the 2-position.
In more preferred embodiments, R1 is halide or methyl or higher (C9-C13) alkyl. R1 is selected from halide, CH3, C2H5, CF3, C2F5, n-C3H7 and cyclo-C3H7, preferably halide or CH3, and R2 is selected from H, CH3, C2H5, CF3, C2F5, n-C3H7 and cyclo-C3H7, more preferably R1 is halide or CH3, and R2 are selected from H, CH3, C2H5, or CF3.
In more preferred embodiments, R1 is Cl or Br, or if greater ETB activity is preferred a higher alkyl (C9H19 to C13H27; R2 is selected from H, CH3, C2H5, CF3, C2F5, n-C3H7, cyclo-C3H7, nC13H27 and nC9H19 In yet more preferred embodiments, R1 is Br, Cl or C9H19 to C13H27; R2 is H, CH3, C2H5, or CF3.
The biphenyl compounds provided herein are generally ETB active or ETB selective (see, e.g., Table 2); i.e. the compounds provided herein inhibit binding of endothelin to ETB receptors at concentrations about 10- to about 30-fold less than they inhibit binding of endothelin to ETA receptors. In particular the 4-biphenylsulfonamides are ETB selective.
In general in all embodiments herein, 4-haloisoxazolyl sulfonamides exhibit substantially enhanced activity with respect to at least one of the ET receptors (about two-fold to twenty-fold greater activity), as assessed by assays, such as those provided herein, that measure binding to ETA and/or ETB receptors, compared to corresponding sulfonamides in which the substituent at the 4 position in the isoxazolyl is other than halo, such as alkyl. For example: the IC50 of N-(3,4-dimethyl-5-isoxazolyl)-2-biphenylsulfonamide for ETA receptors is about 0.008 xcexcM, whereas, the IC50 of N-(4-bromo-3-methyl-5-isoxazolyl)-2-biphenylsulfonamide is about 0.0016 xcexcM (see, Table below); and (3) the IC50 of N-(3,4-dimethyl-5-isoxazolyl)-3-biphenylsulfonamide for ETB receptors is about 3.48 xcexcM; whereas, the IC50 of N-(4-bromo-3-methyl-5-isoxazolyl)-3-biphenylsulfonamide for ETB receptors is about 0.76 xcexcM and the IC50 of N-(4-chloro-3-methyl-5-isoxazolyl)-3-biphenylsulfonamide for ETB receptors is about 0.793 xcexcM (see, Table below).
Exemplary biphenyl sulfonamides are the following and those set forth in Table 2, and include, but are not limited to:
N-(3-methyl-5-isoxazolyl)-4xe2x80x2-methylphenyl-4-biphenylsulfonamide, N-(4-bromo-3-methyl-5-isoxazolyl)-4xe2x80x2-methylphenyl-4-biphenylsulfonamide, N-(4-chloro-3-methyl-5-isoxazolyl)-4xe2x80x2-methylphenyl-4-biphenylsulfonamide, (3-methyl-5-isoxazolyl)-4xe2x80x2-trifluoromethylphenyl-4-biphenylsulfonamide, (4-bromo-3-methyl-5-isoxazolyl)-4xe2x80x2-trifluoromethylphenyl-4-biphenylsulfonamide, (3-methyl-5-isoxazolyl)-4xe2x80x2-methyoxyphenyl-4-biphenylsulfonamide, (4-bromo-3-methyl-5-isoxazolyl)-4xe2x80x2-methoxyphenyl-4-biphenylsulfonamide, (4-bromo-3-methyl-5-isoxazolyl)-3xe2x80x2-methoxyphenyl-4-biphenylsulfonamide, (4-bromo-3-methyl-5-isoxazolyl)-2xe2x80x2-methoxyphenyl-4-biphenylsulfonamide, N-(4-bromo-3-methyl-5-isoxazolyl)-3xe2x80x2,4xe2x80x2-methylenedioxyphenyl-4-biphenylsulfonamide and (4-bromo-3-methyl-5-isoxazolyl)-3xe2x80x2-methylphenyl-4-biphenylsulfonamide. Corresponding 4-chloro and 4-fluoro isoxazolyl compounds are also encompassed herein.
Exemplary biphenyl compounds were tested using the exemplified assays (see, EXAMPLES) and the results, which are intended to be exemplary or provided for comparison with compounds provided herein, and are not limiting, are as set forth in the following table (Table 2):
Preferred compounds are those in which Ar2 is a 4-biphenyl in which, referring to formula VII and at least one substituent R13 is at the para position. Preferred substituents are loweralkyl, halo loweralkyl and lower alkoxy. Such compounds are ETB active.
The preparation of the above and other compounds that possess the requisite activities are set forth in the Examples.
B. Preparation of the Compounds
The preparation of some of the above and other compounds that possess the requisite activities are set forth in the Examples. Compounds whose synthesis is not explicitly exemplified can be synthesized by routine modification of one or more methods described in detail in the Examples by substituting appropriate readily available reagents.
The preparation of the above compounds are described in detail in the examples. Any such compound or similar compound may be synthesized according to a method discussed in general below and set forth in the Examples by selecting appropriate starting materials as exemplified.
In general, most of the syntheses involve the condensation of a sulfonyl chloride with an aminoisoxazole in dry pyridine or in tetrahydrofuran (THF) and sodium hydride. The sulfonyl chlorides and aminoisoxazoles either can be obtained commercially or synthesized according to methods described in the Examples or using other methods available to those of skill in this art (see, e.g., U.S. Pat. Nos. 4,659,369, 4,861,366 and 4,753,672).
The N-(alkylisoxazolyl)sulfonamides can be prepared by condensing an aminoisoxazole with a sulfonyl chloride in dry pyridine with or without the catalyst 4-(dimethylamino)pyridine. The N-(3,4-dimethyl-5-isoxazolyl)sulfonamides and N-(4,5-dimethyl-5-isoxazolyl)sulfonamides can be prepared from the corresponding aminodimethylisoxazole, such as 5-amino-3,4-dimethylisoxazole. For example, N-(3,4-dimethyl-5-isoxazolyl)-2-(carbomethoxy)thiophene-3-sulfonamide was prepared from 2-methoxycarbonylthiophene-3-sulfonyl chloride and 5-amino-3,4-dimethyl-isoxazole in dry pyridine.
The N-(4-haloisoxazolyl)sulfonamides can be prepared by condensation of amino-4-haloisoxazole with a sulfonyl chloride in THF with sodium hydride as a base. For example, N-(4-bromo-3-methyl-5-isoxazolyl)thiophene-2-sulfonamide was prepared from 5-amino-4-bromo-3-methylisoxazole and thiophene-2-sulfonyl chloride in THF and sodium hydride. N-(4-bromo-3-methyl-5-isoxazolyl)-5-(3-isoxazolyl)thiophene-2-sulfonamide was prepared from 5-amino-4-bromo-3-methylisoxazole and 5-(3-isoxazolyl)thiophene-2-sulphonyl chloride.
Alternatively, compounds, such as those in which Ar2 is thienyl, fury and pyrrolyl herein, may be prepared by reacting an appropriate sulfonyl chloride with a 5-aminoisoxazole substituted at the 3 and 4 positions, such as 5-amino-4-bromo-3-methylisoxazole, in tetrahydrofuran (THF) solution containing a base, such as sodium hydride. Following the reaction, the THF is removed under reduced pressure, the residue dissolved in water, acidified and extracted with methylene chloride. The organic layer is washed and then dried over anhydrous magnesium sulfate, the solvents are evaporated and the residue is purified by recrystallization using hexanes/ethylacetate to yield pure product.
These sulfonamides also can be prepared from the corresponding sulfonyl chloride and the aminoisoxazole in pyridine with or without a catalytic amount of 4-dimethylaminopyridine (DMAP). In some cases, the bis-sulfonyl compound is obtained as the major or exclusive product. The bis-sulfonated products can be readily hydrolyzed to the sulfonamide using aqueous sodium hydroxide and a suitable co-solvent, such as methanol or tetrahydrofuran, generally at room temperature. For example:
(a) N-(4-bromo-3-methyl-5-isoxazolyl)-2-(N-phenyl-aminocarbonyl)thiophene-3-sulfonamide was prepared from N-(4-bromo-3-methyl-5-isoxazolyl)-2-carboxylthiophene-3-sulfonamide and aniline and 1-ethyl-3xe2x80x2-[3-dimethylaminopropyl]carbodiimide (EDCI). N-(4-bromo-3-methyl-5-isoxazolyl)-2-[(4-methoxyphenyl)aminocarbonyl]thiophene-3-sulfonamide was prepared from 4-methoxyaniline, N,Nxe2x80x2-diisopropylethylamine and N-(4-bromo-3-methyl-5-isoxazolyl)-2-carboxylthiophene-3-sulfonamide. N-(4-bromo-3-methyl-5-isoxazolyl)-2-(benzylaminocarbonyl)-thiophene-3-sulfonamide was prepared from N-(4-bromo-3-methyl-5-isoxazolyl)-2-carboxylthiophene-3-sulfonamide and benzylamine as described above.
N-(4-bromo-3-methyl-5-isoxazolyl)-2-carboxylthiophene-3-sulfonamide was prepared from N-(4-bromo-3-methyl-5-isoxazolyl)-2-(carbomethoxy)thiophene-3-sulfonamide, which was prepared from the condensation of 5-amino-4-bromo-3-methylisoxazole and 2-(carbomethoxy)thiophene-3-sulfonyl chloride.
(b) N-(4-bromo-3-methyl-5-isoxazolyl)-1-(4xe2x80x2-isopropylphenyl)pyrrole-2-sulfonamide and N-(4-bromo-3-methyl-5-isoxazolyl)-1-(4xe2x80x2-isopropylphenyl)pyrrole-3-sulfonamide were prepared from 5-amino-4-bromo-3-methylisoxazole and a mixture of 1-(4xe2x80x2-isopropylphenyl)pyrrole-2-sulfonyl chloride and 1-(4xe2x80x2-isopropylphenyl)pyrrole-3-sulfonyl chloride. These sulfonyl chlorides were prepared from 1-(4xe2x80x2-isopropylphenyl)pyrrole-2-sulfonic acid in phosphorus oxychloride and phosphorus pentachloride. 1-(4xe2x80x2-isopropylphenyl)pyrrole-2-sulfonic acid was prepared from 1-(4xe2x80x2-isopropylphenyl)pyrrole and chlorosulfonic acid. 1-(4xe2x80x2-isopropylphenyl)pyrrole was prepared from 4-isopropylaniline and 2,5-dimethoxytetrahydrofuran.
Prodrugs and other derivatives of the compounds suitable for administration to humans may also be designed and prepared by methods known to those of skill in the art (see, e.g., Nogrady (1985) Medicinal Chemistry A Biochemical Approach, Oxford University Press, New York, pages 388-392).
Compounds described herein have been synthesized and tested for activity in In vitro assays and, in some cases, in in vivo animal models. Nuclear magnetic resonance spectroscopic (NMR), mass spectrometric, infrared spectroscopic and high performance liquid chromatographic analyses indicated that the synthesized compounds have structures consistent with those expected for such compounds and are generally at least about 98% pure. All of the compounds exemplified or described herein exhibited activity as endothelin antagonists.
C. Evaluation of the Bioactivity of the Compounds
Standard physiological, pharmacological and biochemical procedures are available for testing the compounds to identify those that possess any biological activities of an endothelin peptide or the ability to interfere with or inhibit endothelin peptides. Compounds that exhibit in vitro activities, such as the ability to bind to endothelin receptors or to compete with one or more of the endothelin peptides for binding to endothelin receptors can be used in the methods for isolation of endothelin receptors and the methods for distinguishing the specificities of endothelin receptors, and are candidates for use in the methods of treating endothelin-mediated disorders.
Thus, other preferred compounds of formulas I and II, in addition to those specifically identified herein, that are endothelin antagonists or agonists may be identified using such screening assays.
1. Identifying Compounds That Modulate the Activity of an Endothelin Peptide
The compounds are tested for the ability to modulate the activity of endothelin-1. Numerous assays are known to those of skill in the art for evaluating the ability of compounds to modulate the activity of endothelin (see, e., U.S. Pat. No. 5,114,918 to Ishikawa et al.; EP A1 0 436 189 to BANYU PHARMACEUTICAL CO., LTD. (Oct. 7, 1991); Borges et al. (1989) Eur. J. Pharm. 165: 223-230; Filep et al. (1991) Biochem. Biophys. Res. Commun. 177: 171-176). In vitro studies may be corroborated with in vivo studies (see, e.g., U.S. Pat. No. 5,114,918 to Ishikawa et al.; EP A1 0 436 189 to BANYU PHARMACEUTICAL CO., LTD. (Oct. 7, 1991)) and pharmaceutical activity thereby evaluated. Such assays are described in the Examples herein and include the ability to compete for binding to ETA and ETB receptors present on membranes isolated from cell lines that have been genetically engineered to express either ETA or ETB receptors on their cell surfaces.
The properties of a potential antagonist may be assessed as a function of its ability to inhibit an endothelin induced activity in vitro using a particular tissue, such as rat portal vein and aorta as well as rat uterus, trachea and vas deferens (see e.g., Borges, R., Von Grafenstein, H. and Knight, D. E., xe2x80x9cTissue selectivity of endothelin,xe2x80x9d Eur. J. Pharmacol 165:223-230, (1989)). The ability to act as an endothelin antagonist in vivo can be tested in hypertensive rats, ddy mice or other recognized animal models (see, Kaltenbronn et al. (1990) J. Med. Chem. 33:838-845, see, also, U.S. Pat. No. 5,114,918 to Ishikawa et al.; and EP A1 0 436 189 to BANYU PHARMACEUTICAL CO., LTD (Oct. 7, 1991); see, also Bolger et al. (1983) J. Pharmacol. Exp. Ther. 225291-309). Using the results of such animal studies, pharmaceutical effectiveness may be evaluated and pharmaceutically effective dosages determined. A potential agonist may also be evaluated using in vitro and in vivo assays known to those of skill in the art.
Endothelin activity can be identified by the ability of a test compound to stimulate constriction of isolated rat thoracic aorta (Borges et al. (1989) xe2x80x9cTissue selectivity of endothelinxe2x80x9d Eur. J. Pharmacol. 165: 223-230). To perform the assay, the endothelium is abraded and ring segments mounted under tension in a tissue bath and treated with endothelin in the presence of the test compound. Changes in endothelin induced tension are recorded. Dose response curves may be generated and used to provide information regarding the relative inhibitory potency of the test compound. Other tissues, including heart, skeletal muscle, kidney, uterus, trachea and vas deferens, may be used for evaluating the effects of a particular test compound on tissue contraction.
Endothelin isotype specific antagonists may be identified by the ability of a test compound to interfere with endothelin binding to different tissues or cells expressing different endothelin-receptor subtypes, or to interfere with the biological effects of endothelin or an endothelin isotype (Takayanagi et al. (1991) Reg. Pep. 32: 23-37, Panek et al. (1992) Biochem. Biophys. Res. Commun. 183: 566-571). For example, ETB receptors are expressed in vascular endothelial cells, possibly mediating the release of prostacyclin and endothelium-derived relaxing factor (De Nucci et al. (1988) Proc. Natl. Acad. Sci. USA 85:9797). ETA receptors are not detected in cultured endothelial cells, which express ETB receptors.
The binding of compounds or inhibition of binding of endothelin to ETB receptors can be assessed by measuring the inhibition of endothelin-1-mediated release of prostacyclin, as measured by its major stable metabolite, 6-keto PGF1a, from cultured bovine aortic endothelial cells (see, e., Filep et al. (1991) Biochem. and Biophys Res. Commun. 177: 171-176). Thus, the relative affinity of the compounds for different endothelin receptors may be evaluated by determining the inhibitory dose response curves using tissues that differ in receptor subtype.
Using such assays, the relative affinities of the compounds for ETA receptors and ETB receptors have been and can be assessed. Those that possess the desired properties, such as specific inhibition of binding of endothelin-1, are selected. The selected compounds that exhibit desirable activities may be therapeutically useful and are tested for such uses using the above-described assays from which in vivo effectiveness may be evaluated (see, e.g., U.S. Pat. Nos. 5,248,807; 5,240,910; 5,198,548; 5,187,195; 5,082,838; 5,230,999; published Canadian Application Nos. 2,067,288 and 2071193; published Great Britain Application No. 2,259,450; Published International PCT Application No. WO 93/08799; Benigi et al. (1993) Kidney International 44:440-444; and Nirei et al. (1993) Life Sciences 52:1869-1874). Compounds that exhibit in vitro activities that correlate with in vivo effectiveness will then be formulated in suitable pharmaceutical compositions and used as therapeutics.
The compounds also may be used in methods for identifying and isolating endothelin-specific receptors and aiding in the design of compounds that are more potent endothelin antagonists or agonists or that are more specific for a particular endothelin receptor.
2. Isolation of Endothelin Receptors
A method for identifying endothelin receptors is provided. In practicing this method, one or more of the compounds is linked to a support and used in methods of affinity purification of receptors. By selecting compounds with particular specificities, distinct subclasses of ET receptors may be identified.
One or more of the compounds may be linked to an appropriate resin, such as Affi-gel, covalently or by other linkage, by methods known to those of skill in the art for linking endothelin to such resins (see, Schvartz et al. (1990) Endocrinology 126: 3218-3222). The linked compounds can be those that are specific for ETA or ETB receptors or other subclass of receptors.
The resin is pre-equilibrated with a suitable buffer generally at a physiological pH (7 to 8). A composition containing solubilized receptors from a selected tissue are mixed with the resin to which the compound is linked and the receptors are selectively eluted. The receptors can be identified by testing them for binding to an endothelin isopeptide or analog or by other methods by which proteins are identified and characterized. Preparation of the receptors, the resin and the elution method may be performed by modification of standard protocols known to those of skill in the art (see, e.g., Schvartz et al. (1990) Endocrinology 126: 3218-3222).
Other methods for distinguishing receptor type based on differential affinity to any of the compounds herein are provided. Any of the assays described herein for measuring the affinity of selected compounds for endothelin receptors may also be used to distinguish receptor subtypes based on affinity for particular compounds provided herein. In particular, an unknown receptor may be identified as an ETA or ETB receptor by measuring the binding affinity of the unknown receptor for a compound provided herein that has a known affinity for one receptor over the other. Such preferential interaction is useful for determining the particular disease that may be treated with a compound prepared as described herein. For example, compounds with high affinity for ETA receptors and little or no affinity for ETB receptors are candidates for use as hypertensive agents; whereas, compounds that preferentially interact with ETB receptors are candidates for use as anti-asthma agents.
D. Formulation and Administration of the Compositions
Effective concentrations of one or more of the sulfonamide compounds of formula I or II or pharmaceutically acceptable salts, esters or other derivatives thereof are mixed with a suitable pharmaceutical carrier or vehicle. In instances in which the compounds exhibit insufficient solubility, methods for solubilizing compounds may be used. Such methods are known to those of skill in this art, and include, but are not limited to, using cosolvents, such as dimethylsulfoxide (DMSO), using surfactants, such as tween, or dissolution in aqueous sodium bicarbonate. Derivatives of the compounds, such as salts of the compounds or prodrugs of the compounds may also be used in formulating effective pharmaceutical compositions.
The concentrations or the compounds are effective for delivery of an amount, upon administration, that ameliorates the symptoms of the endothelin-mediated disease. Typically, the compositions are formulated for single dosage administration.
Upon mixing or addition of the sulfonamide compound(s), the resulting mixture may be a solution, suspension, emulsion or the like. The form of the resulting mixture depends upon a number of factors, including the intended mode of administration and the solubility of the compound in the selected carrier or vehicle. The effective concentration is sufficient for ameliorating the symptoms of the disease, disorder or condition treated and may be empirically determined.
Pharmaceutical carriers or vehicles suitable for administration of the compounds provided herein include any such carriers known to those skilled in the art to be suitable for the particular mode of administration. In addition, the compounds may be formulated as the sole pharmaceutically active ingredient in the composition or may be combined with other active ingredients.
The active compounds can be administered by any appropriate route, for example, orally, parenterally, intravenously, intradermally, subcutaneously, or topically, in liquid, semi-liquid or solid form and are formulated in a manner suitable for each route of administration. Preferred modes of administration include oral and parenteral modes of administration.
The active compound is included in the pharmaceutically acceptable carrier in an amount sufficient to exert a therapeutically useful effect in the absence of undesirable side effects on the patient treated. The therapeutically effective concentration may be determined empirically by testing the compounds in known in vitro and in vivo systems (see, e.g., U.S. Pat. No. 5,114,918 to Ishikawa et al.; EP A1 0 436 189 to BANYU PHARMACEUTICAL CO., LTD (Oct. 7, 1991); Borges et al. (1989) Eur. J. Pharm. 165: 223-230;: Filep et al. (1991) Biochem. Biophys. Res. Commun. 177: 171-176) and then extrapolated therefrom for dosages for humans.
The concentration of active compound in the drug composition will depend on absorption, inactivation and excretion rates of the active compound, the dosage schedule, and amount administered as well as other factors known to those of skill in the art. For example, the amount that is delivered is sufficient to treat the symptoms of hypertension. The effective amounts for treating endothelin-mediated disorders are expected to be higher than the amount of the sulfonamide compound that would be administered for treating bacterial infections.
Typically a therapeutically effective dosage should produce a serum concentration of active ingredient of from about 0.1 ng/ml to about 50-100 xcexcg/ml. The pharmaceutical compositions typically should provide a dosage of from about 0.01 mg to about 2000 mg of compound per kilogram of body weight per day. The active ingredient may be administered at once, or may be divided into a number of smaller doses to be administered at intervals of time. It is understood that the precise dosage and duration of treatment is a function of the disease being treated and may be determined empirically using known testing protocols or by extrapolation from in vivo or in vitro test data. It is to be noted that concentrations and dosage values may also vary with the severity of the condition to be alleviated. It is to be further understood that for any particular subject, specific dosage regimens should be adjusted over time according to the individual need and the professional judgment of the person administering or supervising the administration of the compositions, and that the concentration ranges set forth herein are exemplary only and are not intended to limit the scope or practice of the claimed compositions.
If oral administration is desired, the compound should be provided in a composition that protects it from the acidic environment of the stomach. For example, the composition can be formulated in an enteric coating that maintains its integrity in the stomach and releases the active compound in the intestine. The composition may also be formulated in combination with an antacid or other such ingredient.
Oral compositions will generally include an inert diluent or an edible carrier and may be compressed into tablets or enclosed in gelatin capsules. For the purpose of oral therapeutic administration, the active compound or compounds can be incorporated with excipients and used in the form of tablets, capsules or troches. Pharmaceutically compatible binding agents and adjuvant materials can be included as part of the composition.
The tablets, pills, capsules, troches and the like can contain any of the following ingredients, or compounds of a similar nature: a binder, such as microcrystalline cellulose, gum tragacanth and gelatin; an excipient such as starch and lactose, a disintegrating agent such as, but not limited to, alginic acid and corn starch; a lubricant such as, but not limited to, magnesium stearate; a glidant, such as, but not limited to, colloidal silicon dioxide; a sweetening agent such as sucrose or saccharin; and a flavoring agent such as peppermint, methyl salicylate, and fruit flavoring.
When the dosage unit form is a capsule, it can contain, in addition to material of the above type, a liquid carrier such as a fatty oil. In addition, dosage unit forms can contain various other materials which modify the physical form of the dosage unit, for example, coatings of sugar and other enteric agents. The compounds can also be administered as a component of an elixir, suspension, syrup, wafer, chewing gum or the like. A syrup may contain, in addition to the active compounds, sucrose as a sweetening agent and certain preservatives, dyes and colorings and flavors.
The active materials can also be mixed with other active materials which do not impair the desired action, or with materials that supplement the desired action, such as antacids, H2 blockers, and diuretics. For example, if the compound is used for treating asthma or hypertension, it may be used with other bronchodilators and antihypertensive agents, respectively.
Solutions or suspensions used for parenteral, intradermal, subcutaneous, or topical application can include any of the following components: a sterile diluent, such as water for injection, saline solution, fixed oil, polyethylene glycol, glycerine, propylene glycol or other synthetic solvent; antimicrobial agents, such as benzyl alcohol and methyl parabens; antioxidants, such as ascorbic acid and sodium bisulfite; chelating agents, such as ethylenediaminetetraacetic acid (EDTA); buffers, such as acetates, citrates and phosphates; and agents for the adjustment of tonicity such as sodium chloride or dextrose. Parenteral preparations can be enclosed in ampules, disposable syringes or multiple dose vials made of glass, plastic or other suitable material.
If administered intravenously, suitable carriers include physiological saline or phosphate buffered saline (PBS), and solutions containing thickening and solubilizing agents, such as glucose, polyethylene glycol, and polypropylene glycol and mixtures thereof. Liposomal suspensions, including tissue-targeted liposomes, may also be suitable as pharmaceutically acceptable carriers. These may be prepared according to methods known to those skilled in the art. For example, liposome formulations may be prepared as described in U.S. Pat. No. 4,522,811.
The active compounds may be prepared with carriers that protect the compound against rapid elimination from the body, such as time release formulations or coatings. Such carriers include controlled release formulations, such as, but not limited to, implants and microencapsulated delivery systems, and biodegradable, biocompatible polymers, such as collagen, ethylene vinyl acetate, polyanhydrides, polyglycolic acid, polyorthoesters, polylactic acid and others. Methods for preparation of such formulations are known to those skilled in the art.
The compounds may be formulated for local or topical application, such as for topical application to the skin and mucous membranes, such as in the eye, in the form of gels, creams, and lotions and for application to the eye or for intracisternal or intraspinal application. Such solutions, particularly those intended for ophthalmic use, may be formulated as 0.01%-10% isotonic solutions, pH about 5-7, with appropriate salts. The compounds may be formulated as aerosols for topical application, such as by inhalation (see, e.g., U.S. Pat. Nos. 4,044,126, 4,414,209, and 4,364,923, which describe aerosols for delivery of a steroid useful for treatment inflammatory diseases, particularly asthma).
Finally, the compounds may be packaged as articles of manufacture containing packaging material, a compound provided herein, which is effective for antagonizing the effects of endothelin, ameliorating the symptoms of an endothelin-mediated disorder, or inhibiting binding of an endothelin peptide to an ET receptor with an IC50 of less than about 10 xcexcM, within the packaging material, and a label that indicates that the compound or salt thereof is used for antagonizing the effects of endothelin, treating endothelin-mediated disorders or inhibiting the binding of an endothelin peptide to an ET receptor.
The following examples are included for illustrative purposes only and are not intended to limit the scope of the invention.